Power supplies / Compare

Montech Century II 850W vs Seasonic CORE GX-850 (2024)

A

Product A: Montech

Century II 850W

54 of 66 known

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B

Product B: Seasonic

CORE GX-850 (2024)

56 of 66 known

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Only differences

AMontech Century II 850W

BSeasonic CORE GX-850 (2024)

General

7 of 12 differ

Series

Century II1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026

CORE GX2Press releasefunkykit.com/news/seasonic-launches-updated-core-atx-3-psu-series-with-atx-3-1-and-pcie-gen-5-1Read 15 October 2026The release calls the family the CORE GX ATX 3 series, in four outputs from 1000 W to 650 W.

Model numbersiMaker identifiers for this exact model and its listed variants. Excludes sibling models and other generations.

Century II 850W1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Specifications tab: Model Name Century II 850W. The maker prints no part number.

SRP-CGX851-A5A32SF, SRP-CGX851-A5A32SF-W3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026Article number SRP-CGX851-A5A32SF, the black unit.8Retailer pageldlc.com/en/product/PB00657446.htmlRead 15 October 2026Model SRP-CGX851-A5A32SF for the black Seasonic CORE GX ATX 3 (2024) 850 W. The page says the product was referenced on December 5, 2024.10Retailer pageparadigit.ie/seasonic-core-gx-atx3-1-white-850-w/21750146/productRead 15 October 2026Product number manufacturer SRP-CGX851-A5A32SF-W for the white unit.

GTIN / EAN

47105627472631Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Specifications tab: EAN 4710562747263.

4711173878476, 47111738787283Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026EAN 4711173878476 for SRP-CGX851-A5A32SF (black). The check digit is valid.9Retailer pagemultitronic.fi/en/products/4589683/seasonic-core-gx-850w--virtalahde--80-plus-goldRead 15 October 2026EAN 4711173878728, product colour white. The check digit is valid.

AnnouncediThe maker's first announcement of this model. This is separate from first retail availability.

15 April 20252Press releasemontechpc.com/news-century-iiRead 14 October 2026Launch article dated 2025-04-15. The unit is available from that day (see the Funkykit launch report).

6 December 20242Press releasefunkykit.com/news/seasonic-launches-updated-core-atx-3-psu-series-with-atx-3-1-and-pcie-gen-5-1Read 15 October 2026Press release dated December 6, 2024.

Status

Available8Retailer pagemaxmybuild.com/power-supplies/montech-century-ii-850wRead 14 October 2026Listing shows $89.90 at Amazon and Newegg, updated 14 Oct 2026. Scan UK lists only an open-box unit and calls the model end of life. Tom's Hardware, in its review of 7 September 2026, lists it at Amazon, Newegg and Best Buy.

Available3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026The page lists the black unit in stock with 2 pieces.

PredecessoriThe model this one directly replaced, in the same line, tier and size, as the maker or a trusted review names it.

Not available

Not available

SuccessoriThe model that directly replaced this one, in the same line, tier and size. A revision such as a Slim or OLED model does not count when a next generation exists.

Not available

Not available

Launch price (US)iThe maker's US launch MSRP for the stated configuration, excluding tax. Current store prices and later discounts do not qualify.

$89.92Press releasemontechpc.com/news-century-iiRead 14 October 2026Article: Starting at just $89.9. Funkykit lists the 850W model at US$ 89.9, the lowest of the three launch models. US price, no sales tax.3Press articlefunkykit.com/news/montech-introduces-century-ii-power-supplyRead 14 October 2026Century II 850 W: US$ 89.9. The 1050 W is US$ 109.9 and the 1200 W is US$ 129.9.

From $129.992Press releasefunkykit.com/news/seasonic-launches-updated-core-atx-3-psu-series-with-atx-3-1-and-pcie-gen-5-1Read 15 October 20269Retailer pagemultitronic.fi/en/products/4589683/seasonic-core-gx-850w--virtalahde--80-plus-goldRead 15 October 202610Retailer pageparadigit.ie/seasonic-core-gx-atx3-1-white-850-w/21750146/productRead 15 October 2026

Launch price (EU)iThe maker's euro launch price for the stated configuration, including VAT as published. Current store prices and later discounts do not qualify.

Not available

From €129.92Press releasefunkykit.com/news/seasonic-launches-updated-core-atx-3-psu-series-with-atx-3-1-and-pcie-gen-5-1Read 15 October 20269Retailer pagemultitronic.fi/en/products/4589683/seasonic-core-gx-850w--virtalahde--80-plus-goldRead 15 October 202610Retailer pageparadigit.ie/seasonic-core-gx-atx3-1-white-850-w/21750146/productRead 15 October 2026

MarketsiISO country or region codes where this exact model or variant is sold. A source page's language does not establish availability.

Not available

US, EU2Press releasefunkykit.com/news/seasonic-launches-updated-core-atx-3-psu-series-with-atx-3-1-and-pcie-gen-5-1Read 15 October 2026The release lists a USA price and an EU price for the black unit and a rest of the world price that names no country. Only US and EU are stored.

ColoursiThe maker's own colour names

Metallic Silver1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Overview text: a sleek metallic silver finish. The maker names no other colour for this wattage.

Black, White2Press releasefunkykit.com/news/seasonic-launches-updated-core-atx-3-psu-series-with-atx-3-1-and-pcie-gen-5-1Read 15 October 2026Available in black and white.

Form factoriThe physical size standard that decides what fits in the case. An ATX unit is 150 × 86 mm at the back. An SFX unit is 125 × 63.5 mm.

ATX1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Specifications tab: Form Factor ATX (140).5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026DUT Information: Type ATX12V. The maker lists form factor ATX (140).

ATX3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026The page copies Seasonic's spec table. Form Factor ATX/EPS, 140 x 150 x 86 mm, which is the ATX back face of 150 x 86 mm.6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Type ATX12V.

ATX versioniThe ATX12V design guide revision the maker claims compliance with. A 16-pin GPU cable alone does not establish ATX 3.x. A Cybenetics report that withholds its ATX badge does not change the maker's claim. It goes in the source note.

ATX 3.11Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Overview: ATX 3.1 and PCIe 5.1 platform support. The 80 PLUS certificate type line reads ATX 3.0, ATX 3.1.

ATX 3.12Press releasefunkykit.com/news/seasonic-launches-updated-core-atx-3-psu-series-with-atx-3-1-and-pcie-gen-5-1Read 15 October 2026The units comply with the latest ATX 3.1 and PCIe Gen 5.1 standards.7Certification listclearesult.com/80plus/sites/80plus/files/manufacturer-certificate/SEA%20SONIC%20ELECTRONICS%20CO.%20LTD._SRP-CGX851-A5A32SF_850W_SOCE%207565_Report_0.pdfRead 15 October 2026The list names the form factor ATX 3.1.

PCIe CEM versioniThe PCI Express card power revision the maker claims, as printed next to the ATX version. It sets the GPU power connector rules. It is not a slot speed. A reviewer's statement is not enough.

PCIe 5.11Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Overview: ATX 3.1 and PCIe 5.1 platform support.

PCIe 5.12Press releasefunkykit.com/news/seasonic-launches-updated-core-atx-3-psu-series-with-atx-3-1-and-pcie-gen-5-1Read 15 October 2026The units comply with PCIe Gen 5.1.

Modular cablesiFull means every cable detaches. Semi means some cables are fixed, usually the 24-pin and CPU cables.

Fully modular1Maker product pagemontechpc.com/century-ii-850wRead 14 October 20265Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026DUT Information: Cable Design Fully Modular.

Fully modular2Press releasefunkykit.com/news/seasonic-launches-updated-core-atx-3-psu-series-with-atx-3-1-and-pcie-gen-5-1Read 15 October 202680 Plus Gold certified units with a fully modular design and color-matching cables with a braided pattern.6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Cable Design Fully Modular.

Built by (OEM)iThe company that designed and built the unit for the brand, such as CWT or FSP. As named by the maker, a teardown review or a Cybenetics report.

Shenzhen Xinweiye Technology (XWY)5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026DUT Information: OEM/ODM Shenzhen Xinweiye Technology Co., Ltd. Tom's Hardware calls the company XWY.7Reviewtomshardware.com/pc-components/power-supplies/montech-century-ii-gold-850w-atx-3-1-power-supply-reviewRead 14 October 2026Internal Design: the OEM is Shenzhen Xinweiye Technology Co., typically referred to as XWY.

Seasonic6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026DUT Information: OEM/ODM Seasonic. Parts Description: Manufacturer (OEM) Seasonic.

Power

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Rated continuous poweriThe continuous DC output the maker rates the unit for, such as 850. Peak or power excursion figures are not stored here.

850W1Maker product pagemontechpc.com/century-ii-850wRead 14 October 20265Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Manufacturer-provided information: Rated Power 850 W.

850W3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026Total continuous power 850 W.6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Manufacturer-provided information: Rated Power 850 W.

Full power rated up toiThe ambient temperature up to which the maker rates full continuous power, such as 50 °C. A review table that prints 0-50 °C with no maker source is not enough. An operating temperature range that does not say full power is not enough. A maker table with load steps gives the full-load row, such as 40 °C at full load next to 50 °C at 80 percent load. A temperature that a Cybenetics report marks as manufacturer-provided counts as a maker statement.

40°C1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Specifications tab: Operating Temperature 0-40 C. Tom's Hardware prints the power table as Rated @ 40 C. The Cybenetics report leaves its continuous full load temperature row empty.7Reviewtomshardware.com/pc-components/power-supplies/montech-century-ii-gold-850w-atx-3-1-power-supply-reviewRead 14 October 2026Power specifications table titled Rated @ 40 C. Same figure as the maker's operating temperature.

40°C3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026Operating Temperature 0 - 50 C, with derating from 100 % to 80 % linearly from 40 C to 50 C. Full power is therefore rated up to 40 C.4Retailer pageinside-tech.co.uk/power-supplies-2/seasonic-core-gx-v4-850w-80-plus-gold-atx-3-1-modular-psu-with-120mm-fdb-fan-braided-cables-7-year-warranty-blackRead 15 October 2026Operating Temperature 0 - 50 C (derating from 100 % to 80 % from 40 C to 50 C linearly).

12V rail designiHow the maker splits +12V over-current protection. Switchable means the user picks single or multi rail with a switch or in software.

Single rail5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Power Specifications: one +12V column with 70.8A and 849.6W, and one OCP result for 12V.

Single rail6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Power Specifications: one +12V column with 70 A and 840 W, and one 12V OCP result.

+12V max currentiHighest combined current on +12V from the maker's power table. For a multi-rail unit this is the combined total, not one rail.

70.8A1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026DC Output table: +12V 70.8A, 849.6W.5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026

70A3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026DC output: +3.3 V 20 A, +5 V 20 A, +12 V 70 A, -12 V 0.3 A, +5 VSB 3 A.5Reviewkitguru.net/components/power-supplies/zardon/seasonic-core-gx-850-atx-3-reviewRead 15 October 2026Page 3: the +12V rail can deliver 70 A and the +3.3V and +5V 20 A, for a total of 850 W.6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Power Specifications table: +12V 70 A.

+12V max poweriHighest combined power on +12V from the maker's power table.

849.6W1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026DC Output table: +12V 70.8A, 849.6W.5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026

840W4Retailer pageinside-tech.co.uk/power-supplies-2/seasonic-core-gx-v4-850w-80-plus-gold-atx-3-1-modular-psu-with-120mm-fdb-fan-braided-cables-7-year-warranty-blackRead 15 October 2026The page copies Seasonic's spec table. DC output maximum power: +12 V 840 W, with 100 W, 3.6 W and 15 W for the other rows. The listing text names the white version.6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Power Specifications table: +12V 840 W.

+3.3V and +5V combined poweriThe combined limit for the +3.3V and +5V rails from the maker's power table. A table that prints the same figure under both rails, as be quiet! does, shows one shared limit, so the figure is stored once and not added.

100W1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026DC Output table prints +3.3V 20A 100W and +5V 20A 100W. The Cybenetics power table has one merged 100W cell for 3.3V and 5V, so 100W is the combined limit.5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026

100W4Retailer pageinside-tech.co.uk/power-supplies-2/seasonic-core-gx-v4-850w-80-plus-gold-atx-3-1-modular-psu-with-120mm-fdb-fan-braided-cables-7-year-warranty-blackRead 15 October 2026Power output row prints 100 W once for the +3.3 V and +5 V rails, so it is one shared limit.6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Power Specifications table: one merged 100 W cell for 3.3V and 5V, 20 A each.

+5V standby currentiHighest current on the +5VSB standby rail. It powers USB charging and wake functions while the PC is off.

3A1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026DC Output table: +5VSB 3A, 15W.5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026

3A3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026DC output: +5 VSB 3 A.6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Power Specifications table: 5VSB 3 A, 15 W.

AC input voltageiThe rated AC input range, such as 100 to 240 V.

Lowest100Highest240V1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026AC Input 100-240 VAC, 50-60 Hz, 10 A max.5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Manufacturer-provided information: 100-240 Vrms, 10 A, 50-60 Hz.

Lowest100Highest240V3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026AC input 100 V - 240 V, 11 - 5.5 A, 50 Hz - 60 Hz.4Retailer pageinside-tech.co.uk/power-supplies-2/seasonic-core-gx-v4-850w-80-plus-gold-atx-3-1-modular-psu-with-120mm-fdb-fan-braided-cables-7-year-warranty-blackRead 15 October 2026AC input 100 V - 240 V, 11 - 5.5 A, 50 Hz - 60 Hz.6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Manufacturer-provided information: 100-240 Vrms, 5.5-11 A, 50-60 Hz.

Alternative low power mode (ALPM)iThe maker or a Cybenetics report states support for the ATX alternative low power mode used by Modern Standby.

Yes5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Temperature and Compliance Info: ALPM compatible, checked.

Yes6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Temperature and Compliance Info: ALPM compatible, checked.

Certifications

0 of 5 differ

80 PLUS ratingiThe 80 PLUS level. When the 80 PLUS listing or certificate and the maker claim differ, store the listing level and put the claim and test voltage in the source note. When a model has several 80 PLUS entries, such as a newer test at a higher level, use the newest entry that matches the current maker documents.

80 PLUS Gold6Certification listclearesult.com/80plus/sites/80plus/files/manufacturer-certificate/MONTECH_CENTURY%20II%20850W_850W_SOCE%207850_Report.pdfRead 14 October 202680 PLUS ID 7850, model CENTURY II 850W: Gold at 115V, test date 2025-06-04. The certificate lists no sample serial. The maker's own product page says Platinum, which is the Cybenetics level.

80 PLUS Gold7Certification listclearesult.com/80plus/sites/80plus/files/manufacturer-certificate/SEA%20SONIC%20ELECTRONICS%20CO.%20LTD._SRP-CGX851-A5A32SF_850W_SOCE%207565_Report_0.pdfRead 15 October 202680 PLUS ID 7565, model SRP-CGX851-A5A32SF, 850 W, Gold at 115V, certified 09/24/2024, 91.43 percent at 50 percent load. The list has no sample serial, so the match is by model code and wattage.

Cybenetics efficiency at 115ViThe Cybenetics ETA level from the 115V test. The Cybenetics report wins over the maker's claim.

Cybenetics Platinum5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Report 25PS2813A, certification ID 252813, issued May 13, 2025. The database name is Montech Century II Gold 850 ATX3. The badge is ETA Platinum at 115V.

Cybenetics Platinum6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Report issued Mar 6, 2025, lab ID SS85002750. The database name is Core GX-850 ATX3 and the report has no sample serial. The database lists ETA Platinum at 115V. The sample has the fan, capacitors and cable set of the CORE GX-850 that KitGuru reviewed.

Cybenetics efficiency at 230ViThe Cybenetics ETA level from the 230V test. The 230V thresholds are higher, so the level can differ from the 115V level. The Cybenetics report wins over the maker's claim.

Cybenetics Platinum5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026ETA Platinum at 230V.

Cybenetics Platinum6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026The database lists ETA Platinum at 230V.

Cybenetics noise at 115ViThe Cybenetics LAMBDA level from the 115V test. A++ is the quietest. The Cybenetics report wins over the maker's claim.

A-5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026LAMBDA A- at 115V.

A-6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026The database lists LAMBDA A- at 115V. Seasonic's spec table said TBA at launch.

Cybenetics noise at 230ViThe Cybenetics LAMBDA level from the 230V test. The Cybenetics report wins over the maker's claim.

A-5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026LAMBDA A- at 230V.

A-6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026The database lists LAMBDA A- at 230V.

Measured

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Average efficiency at 115V (measured)iAverage efficiency over the whole load range at 115V input, from more than 1450 load combinations in the Cybenetics method. It is not the peak efficiency or the efficiency at 50% load.

89.8%5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Average over more than 1450 load combinations at 115V. Tested May 10, 2025, ambient 28-32 C. The report lists no sample serial.

89.073%6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Average over more than 1450 load combinations at 115V. Sample received Feb 11, 2025, tested Feb 20, 2025, ambient 28-32 C.

Average efficiency at 230V (measured)iThe same average efficiency at 230V input.

91.84%5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Average over more than 1450 load combinations at 230V.

91.095%6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Average over more than 1450 load combinations at 230V.

Light-load efficiency at 115V (measured)iEfficiency at a 10 W load for units up to 500 W, or at a 2% load for larger units, at 115V input. This is the ATX light-load test.

70.357%5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Efficiency at 2% load (more than 500 W unit) at 115V.

71.934%6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Efficiency at 2% load (more than 500 W unit) at 115V.

Average power factor at 115V (measured)iAverage power factor over the whole load range at 115V input. 1 is the best possible value.

0.9855Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Average over more than 1450 load combinations at 115V. At 230V it is 0.945.

0.9776Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Average over more than 1450 load combinations at 115V. At 230V it is 0.943.

Average noise at 115V (measured)iAverage noise over the whole load range at 115V input in the Cybenetics method, at about 30 °C ambient. It is not the noise at full load.

26.89dB(A)5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Average over more than 1450 load combinations at 115V, ambient 28-32 C, Bruel and Kjaer 2270 G4 sound analyzer. The 230V average is 26.26 dBA.

28.17dB(A)6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Average over more than 1450 load combinations at 115V, ambient 28-32 C, Bruel and Kjaer 2270 G4 sound analyzer. The 230V average is 28.19 dBA.

Noise at full load at 115V (measured)iNoise at 100% load at 115V input in the Cybenetics typical load tests. That row often runs at about 45 °C intake. The intake temperature and the fan speed go in the source note. Lower is better.

42.1dB(A)5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Typical load tests at 115V, 100% load row: 42.1 dB(A) at 1698 rpm fan speed, ambient about 30 C.

43.7dB(A)6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Typical load tests at 115V, 100% load row: 43.7 dB(A) at 1729 rpm fan speed, 45.73 C intake temperature.

Standby power with no load at 115V (measured)iPower the unit draws from the wall with the PC off and nothing drawn from +5VSB, at 115V input.

0.073W5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Standby power consumption at 115V with no load on +5VSB: 0.0730 W. At 230V it is 0.1474 W.

0.0665W6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Standby power consumption at 115V with no load on +5VSB: 0.0665 W. At 230V it is 0.1740 W.

Hold-up time (measured)iHow long the outputs stay in regulation after AC power is lost, at maximum continuous load, as printed in the Cybenetics report. The report names no input voltage. The AC loss to PWR_OK time goes in the source note. Higher is better.

22.4ms5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Hold-Up Time and PWR_OK Signal: hold-up time 22.4 ms, AC loss to PWR_OK 14.3 ms, at maximum continuous load.

18ms6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Hold-Up Time and PWR_OK Signal: hold-up time 18.0 ms, AC loss to PWR_OK 14.7 ms.

12V ripple at full load (measured)iPeak-to-peak ripple on the +12V rail at full load and 115V input. Lower is better.

28.25mV5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Non-accredited. 12V ripple at full load at 115V. At 230V it is 29.21 mV.

28.89mV6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Non-accredited. 12V ripple at full load at 115V. At 230V it is 29.48 mV.

12V load regulation (measured)iHow far the +12V voltage moves between light and full load at 115V input. Lower is better.

0.39%5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Non-accredited. 12V load regulation at 115V. At 230V it is 0.27%.

1.14%6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Non-accredited. 12V load regulation at 115V. At 230V it is 1.13%.

Cables and connectors

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CablesiOne row per kind of cable that runs from the PSU to a device. Connector is the plug at the device end. Count is the number of those plugs over all cables in the row. Length runs from the PSU end to the first plug. Adapters that plug into other cables are left out. Use 16-pin PCIe when the maker names a 16-pin GPU cable without saying 12V-2x6 or 12VHPWR. A cable from a 12V-2x6 socket on the PSU to 8-pin plugs is a cable, not an adapter, and counts as PCIe 8-pin. When the maker's documents name one GPU cable both 12VHPWR and 12V-2x6, use 16-pin PCIe and name both in the source note. Cables of one connector kind with different lengths or wire gauges get one row each.

AMontech Century II 850W

Connector	Connectors	Cables	Length to first plug (mm)	Wire gauge	Rated power (W)
ATX 24-pin (20+4)	1	1	590	18AWG	Not available
CPU 8-pin (EPS, 4+4)	2	2	700	18AWG	Not available
PCIe 8-pin (6+2)	4	2	600	18AWG	Not available
12V-2x6	1	1	600	16AWG	600
SATA power	8	2	500	18AWG	Not available
4-pin Molex	4	1	500	18AWG	Not available

Source1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Cables table: 1 motherboard cable with a 20+4 pin plug, 2 CPU cables with one 4+4 pin plug, 2 PCIe cables with two 6+2 pin plugs, 1 12V-2x6 cable, 2 SATA cables with 4 plugs and 1 Molex cable with 4 plugs. Lengths and gauge come from the Cybenetics report.5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Cables and Connectors table: ATX 20+4 pin 590 mm 18AWG, 2 x 4+4 pin EPS 700 mm 18AWG, 2 x 6+2 pin PCIe cables 600 mm then 150 mm with 4 plugs in total 18AWG, 12+4 pin PCIe 600 mm (600W) 16-26AWG, 2 SATA cables of 500 mm plus 3 x 150 mm spacing with 8 plugs in total 18AWG, 1 Molex cable 500 mm plus 3 x 150 mm with 4 plugs 18AWG. The 16-26AWG range of the 12V-2x6 cable includes the thin sideband wires, so the stored gauge is the 16AWG power wire.

BSeasonic CORE GX-850 (2024)

Connector	Connectors	Cables	Length to first plug (mm)	Wire gauge	Rated power (W)
ATX 24-pin (20+4)	1	1	610	16-18AWG	Not available
CPU 8-pin (EPS, 4+4)	2	2	750	16AWG	Not available
PCIe 8-pin (6+2)	1	1	750	16-18AWG	Not available
PCIe 8-pin (6+2)	2	1	700	16-18AWG	Not available
12V-2x6	1	1	700	16AWG	600
SATA power	6	2	455	18AWG	Not available
4-pin Molex	3	1	455	18AWG	Not available

Source5Reviewkitguru.net/components/power-supplies/zardon/seasonic-core-gx-850-atx-3-reviewRead 15 October 2026Page 2 shows Seasonic's Cable Summary slide for the CORE GX ATX 3, 850 W column: MB 610 mm 1 cable with 20+4 pins, CPU 750 mm 2 cables with 4+4 pins, 12V-2x6 700 mm 1 cable, PCIe 750 mm 1 cable with 6+2 pins, PCIe 700 mm 1 cable with 16 pins to 2 x 6+2 pins, SATA 750 mm 2 cables with 3 connectors, Molex 690 mm 1 cable with 3 connectors. The review says both connector types support up to 600 W. The SATA and Molex lengths run to the last plug, so the first-plug lengths come from the Cybenetics report (455 mm for both). The page 3 photo of the modular panel shows one 12-pin PCIe socket, so the 16-pin to dual 8-pin cable shares that socket with the native 12V-2x6 cable. Wire gauges come from Cybenetics.6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Cables and Connectors table: ATX 20+4 pin 620 mm 16-18AWG, 2 x 4+4 pin EPS12V 750 mm 16AWG, one cable with 2 x 6+2 pin PCIe plugs 710 mm 16-18AWG, one 6+2 pin PCIe 750 mm 16-18AWG, 12+4 pin PCIe 700 mm (600W) 16-28AWG, 2 SATA cables of 455+155+155 mm with 6 plugs, one 4-pin Molex cable of 455+125+125 mm with 3 plugs, 18AWG, no in-cable capacitors. The 16-28AWG range of the 12V-2x6 cable includes the thin sideband wires, so the stored gauge is the 16AWG power wire. Seasonic's slide lengths are stored where they are first-plug lengths. Cybenetics measured 620 mm for the 24-pin cable and 710 mm for the dual 8-pin cable.8Retailer pageldlc.com/en/product/PB00657446.htmlRead 15 October 2026Power connectors: 2 x +12V (P8, 2 x P4), 6 x Serial ATA, 1 x ATX 20+4 pin, 3 x Molex (4 pin), 3 x PCI Express 6+2 pin, 1 x PCI Express 16 pin (12V-2x6).

CPU (EPS) connectorsi8-pin or 4+4-pin CPU power plugs.

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PCIe 8-pin connectorsi8-pin or 6+2-pin GPU power plugs. Counts the plugs in the box. Some cables share one PSU socket, which the source note says.

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16-pin GPU connectorsiNative 16-pin GPU power plugs: 12V-2x6, 12VHPWR and 16-pin cables of unstated revision. Adapters are not counted. Counts the plugs in the box. Some cables share one PSU socket, which the source note says.

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1=CalculatedFrom Cables

SATA power connectors

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4-pin Molex connectors

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Cable styleiHow the modular cables are made. Mixed means some cables are sleeved and others flat, such as a sleeved 24-pin cable with flat other cables. From the maker page or a review photo page.

Flat1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Overview: Flat cables and fully modular design.7Reviewtomshardware.com/pc-components/power-supplies/montech-century-ii-gold-850w-atx-3-1-power-supply-reviewRead 14 October 2026The cable bundle is all-black and entirely flat-ribbon in construction.

Sleeved3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026Cable type: Individual Black Cables with Braided Pattern.5Reviewkitguru.net/components/power-supplies/zardon/seasonic-core-gx-850-atx-3-reviewRead 15 October 2026The cables are individually braided.

Fan

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Fan sizeiFrame size of the cooling fan, such as 120, 135 or 140.

135mm1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Specifications tab: Fan Size 135 mm.5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026DUT Information: 135mm Fluid Dynamic Bearing Fan.

120mm2Press releasefunkykit.com/news/seasonic-launches-updated-core-atx-3-psu-series-with-atx-3-1-and-pcie-gen-5-1Read 15 October 2026A 120 mm hydro dynamic bearing fan with Seasonic's Smart and Silent Fan Control.3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026Fan Size 120 mm, Fan Control Smart and Silent Fan Control, life expectancy 25,000 hours at 40 C.5Reviewkitguru.net/components/power-supplies/zardon/seasonic-core-gx-850-atx-3-reviewRead 15 October 2026Page 4: Hong Hua 120 mm Hydro (Fluid) Dynamic Bearing fan, 12 V, 0.58 A, up to 2,200 rpm, model HA1225H12F-Z.6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Fan Hong Hua HA1225H12F-Z, 120 mm.

Fan bearingiUse the maker's bearing name. FDB and S-FDB are fluid dynamic. HDB is hydrodynamic. Noctua SSO and SSO2 are SSO. Corsair Magnetic Dome is magnetic dome. A brand bearing name that fits no option is Other.

Fluid dynamic (FDB)1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Specifications tab: Fan Bearing FDB.5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026DUT Information: 135mm Fluid Dynamic Bearing Fan (HA13525M12SF-Z).

Hydrodynamic (HDB)2Press releasefunkykit.com/news/seasonic-launches-updated-core-atx-3-psu-series-with-atx-3-1-and-pcie-gen-5-1Read 15 October 2026Hydro dynamic bearing fan, 120 mm.3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026Fan Bearing: Hydro Dynamic Bearing.5Reviewkitguru.net/components/power-supplies/zardon/seasonic-core-gx-850-atx-3-reviewRead 15 October 2026Page 4: Hong Hua 120mm Hydro (Fluid) Dynamic Bearing (HDB).6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Fan Hong Hua HA1225H12F-Z, 120 mm, 12 V, 0.58 A, listed as a Fluid Dynamic Bearing fan. Seasonic names it a Hydro Dynamic Bearing.

Fan modeiSemi-passive means the fan stops at low load, often sold as zero RPM, hybrid or 0 dB mode. Fanless means the unit has no fan.

Semi-passive1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Overview: 135 mm FDB fan with Smart Zero Fan mode.5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026DUT Information: Semi-Passive Operation checked (selectable).

Always on5Reviewkitguru.net/components/power-supplies/zardon/seasonic-core-gx-850-atx-3-reviewRead 15 October 2026Page 3: no Hybrid fan control is offered with this unit. The fan spins very slowly at low power and the unit is not audible below about 650 W. Some retailers print a semi-fanless row. Quiet PC copies the same row for the 650, 750 and 850 W columns, even printing 850 W power output in the 650 W column, so it is not used.6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Semi-Passive Operation is not ticked. The typical load tests show 836 rpm at 10 percent load and 833 rpm at 20 percent, so the fan always spins.

Fan mode switchiA button, switch or software setting lets the user turn the semi-passive mode off so the fan always spins. A unit without a semi-passive mode, whose fan the maker says always spins, has no switch, so it is false.

Yes5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026DUT Information: Semi-Passive Operation marked selectable.7Reviewtomshardware.com/pc-components/power-supplies/montech-century-ii-gold-850w-atx-3-1-power-supply-reviewRead 14 October 2026External Appearance: a smaller secondary toggle on the rear lets the user disable the hybrid mode and run the fan continuously.

No5Reviewkitguru.net/components/power-supplies/zardon/seasonic-core-gx-850-atx-3-reviewRead 15 October 2026Page 3: no Hybrid fan control is offered. The unit has no fan mode switch.

Protection and parts

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ProtectionsiProtections the maker lists, or a retailer spec table copies from the maker, plus protections the Cybenetics protection tests show working (UVP, NLO, SIP). The Cybenetics manufacturer list has no OVP or UVP row, so do not build the list from it alone. A protection that is not listed may still exist. No-load covers no-load operation and no-load protection. Fan failure is a maker's fan failure protection or fan safeguard, also when the Cybenetics manufacturer block lists it.

Over-current (OCP), Over-voltage (OVP), Under-voltage (UVP), Over-power (OPP), Over-temperature (OTP), Short-circuit (SCP), No-load (NLO), Surge and inrush (SIP)1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Specifications tab: OPP / OVP / UVP / SCP / OCP / OTP.5Measurementcybenetics.com/evaluations/psus/2813Read 14 October 2026Protection Features (Manufacturer) lists OPP, +12V OCP, OTP, SCP, surge and inrush current protection. Protection tests tick UVP at 90 V and 80 V and NLO. The maker lists OVP, which the report does not test.

Over-current (OCP), Over-voltage (OVP), Under-voltage (UVP), Over-power (OPP), Over-temperature (OTP), Short-circuit (SCP), No-load (NLO), Surge and inrush (SIP)3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026Protection: OPP, OCP, OTP, OVP, SCP, UVP.5Reviewkitguru.net/components/power-supplies/zardon/seasonic-core-gx-850-atx-3-reviewRead 15 October 2026Page 4: OPP, OVP, UVP, OCP, OTP and SCP.6Measurementcybenetics.com/evaluations/psus/2750Read 15 October 2026Protection Features (Manufacturer): OPP, +12V OCP, OTP, SCP, surge and inrush protection. The protection tests tick NLO and SIP (surge MOV, inrush NTC and bypass relay). Fan failure protection is not present. The report has no UVP row, so OVP and UVP come from the maker.

All-Japanese capacitorsiThe maker states that every electrolytic capacitor is from a Japanese maker. A Japanese bulk capacitor alone is not enough. A spec row such as "Japanese capacitors" that names no exception counts.

Yes1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Overview: 100% Japanese capacitors. The launch article says 100% Japanese electrolytic capacitors.2Press releasemontechpc.com/news-century-iiRead 14 October 2026Article: 100% Japanese electrolytic capacitors.

Not available

MTBF (claimed)iThe maker's mean time between failures, such as 100000. An MTTF figure for the whole unit counts too. An MTTF for the fan alone does not. The test temperature goes in the source note.

Not available

100,000h3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026MTBF at 25 C, excluding the fan: 100,000 hours.4Retailer pageinside-tech.co.uk/power-supplies-2/seasonic-core-gx-v4-850w-80-plus-gold-atx-3-1-modular-psu-with-120mm-fdb-fan-braided-cables-7-year-warranty-blackRead 15 October 2026MTBF at 25 C, excl. fan 100,000 hours.

Monitoring and lighting

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Software monitoringiThe unit reports power, temperature or fan data to PC software over a USB or internal connection.

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SoftwareiThe maker's software for monitoring or control.

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Built-in power displayiA screen on the unit that shows live power draw or other readings.

Not available

Not available

RGB lighting

No8Retailer pagemaxmybuild.com/power-supplies/montech-century-ii-850wRead 14 October 2026Listing specs: no RGB. Tom's Hardware and the maker page describe no lighting.

No8Retailer pageldlc.com/en/product/PB00657446.htmlRead 15 October 2026LED RGB: No.

Dimensions and weight

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DimensionsiBody without cables. Width and height are the back face with the AC inlet. Depth is the length into the case, which decides case fit.

Width150Height86Depth140mm(5.9 × 3.4 × 5.5 in)1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Specifications tab: Dimensions (LxWxH) 140 x 150 x 86 mm, so depth 140, width 150, height 86. Tom's Hardware says the unit is 160 mm long. The maker value is stored and retailers copy it.

Width150Height86Depth140mm(5.9 × 3.4 × 5.5 in)3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026140 mm (L) x 150 mm (W) x 86 mm (H). Depth 140, width 150, height 86. The page lists the Cybenetics levels as TBA, so those fields come from the Cybenetics report.5Reviewkitguru.net/components/power-supplies/zardon/seasonic-core-gx-850-atx-3-reviewRead 15 October 2026Page 3: 140 mm x 150 mm x 86 mm.8Retailer pageldlc.com/en/product/PB00657446.htmlRead 15 October 2026Height 86 mm.

WeightiWeight of the unit alone. Use the Hardware Busters figure on hwbusters.com when the maker states none, not a copy on another site. Maker weights that include cables or the box, such as Corsair's, and retailer packed weights are not stored. A net weight counts unless the maker says it includes the cables.

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In the box

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In the boxiItems supplied with this exact model, verbatim. The AC power cord differs per region.

AC power cable, Mounting screws, Velcro-style cable straps, Cable ties, User manual7Reviewtomshardware.com/pc-components/power-supplies/montech-century-ii-gold-850w-atx-3-1-power-supply-reviewRead 14 October 2026In the Box: AC power cable, mounting screws, reusable Velcro-style cable straps, cable ties and a small user manual. Review published 7 September 2026.

Cable ties, Screws for mounting, Regional specific power cable, Literature5Reviewkitguru.net/components/power-supplies/zardon/seasonic-core-gx-850-atx-3-reviewRead 15 October 2026Page 2: the box contains some cable ties, screws for mounting, a regional specific power cable and some literature, with the cables set to one side. Review dated December 31, 2024.

Links

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Product page

www.montechpc.com/century-ii-850w1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026

seasonic.com/core-gx-atx-3-20241Maker product pageseasonic.com/core-gx-atx-3-2024Read 15 October 2026Seasonic's site is blocked for agents, so the page text was not read. The link is the CORE GX ATX 3.1 family page that search results name for this unit. The specs come from Seasonic's launch release, retailer copies of Seasonic's spec table, a cable slide printed in a review, the 80 PLUS list and the Cybenetics report.

Spec sheet

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Manual

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EPREL registration numberiId in the EU energy label database. Each size or model of a series has its own id, so it is per variant.

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Warranty

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Manufacturer warranty (source market)iThe maker's warranty period for the exact SKU or configuration and market named in the source note. It applies only to that stated market, not every regional variant. Statutory consumer rights are excluded. The base term is stored. An extension that needs registration goes in the source note.

10years1Maker product pagemontechpc.com/century-ii-850wRead 14 October 2026Specifications tab: Warranty 10 Years. The page is the global maker page and names no market.

7years2Press releasefunkykit.com/news/seasonic-launches-updated-core-atx-3-psu-series-with-atx-3-1-and-pcie-gen-5-1Read 15 October 2026Sea Sonic's 7-year worldwide manufacturer's warranty.3Retailer pageeshop.enzure.se/seasonic-850w-seasonic-core-srp-cgx851-a5a32sf/cat-p/c/p1005186250Read 15 October 2026Warranty 7 Years.5Reviewkitguru.net/components/power-supplies/zardon/seasonic-core-gx-850-atx-3-reviewRead 15 October 2026Closing page: the Core GX range comes with a 7 year warranty.

Both are also in the API. Back to all power supplies.