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Corsair RMx Series RM1000x Fully Modular Power Supply vs Seasonic FOCUS GX-850 ATX 3 (2024)

Researched, not hands-on tested.How we review ›

all judged against power supplies at a similar price

The Corsair RMx Series RM1000x Fully Modular Power Supply scores 7.7/10 overall, ahead of the Seasonic FOCUS GX-850 ATX 3 (2024) at 6.8/10.

The Corsair RMx Series RM1000x Fully Modular Power Supply leads on quality and protections, cabling and connectors and noise.

They score the same on efficiency and warranty.

Corsair RMx Series RM1000x Fully Modular Power Supply

Corsair RMx Series RM1000x Fully Modular Power Supply

7.7/10verdict: buy

The Corsair RM1000x suits builders putting a high-power graphics card into a new ATX system. It also fits drive-heavy workstations and homelab machines that need many SATA connectors. It is a fully modular 1000W unit with a 10-year warranty and a native 12V-2x6 connector.

Typically about £130 in the UK when we researched itSearch Amazon UK (opens in a new tab, affiliate link)

Affiliate link. As an Amazon Associate I earn from qualifying purchases. Details

Seasonic FOCUS GX-850 ATX 3 (2024)

6.8/10verdict: good, not the best

The Seasonic FOCUS GX-850 ATX 3 (2024) is for builders who want a fully modular 850 W unit with a native 12V-2x6 cable for a current graphics card. It suits buyers who value a 10-year warranty and strong efficiency figures on 230V mains. It is a weaker fit for anyone who puts tight voltage regulation or a consistently quiet fan first.

Typically about £144.95 in the UK when we researched itSearch Amazon UK (opens in a new tab, affiliate link)

Affiliate link. As an Amazon Associate I earn from qualifying purchases. Details

Scores, criterion by criterion

CriterionWeightCorsair RMx Series RM1000x Fully Modular Power SupplySeasonic FOCUS GX-850 ATX 3 (2024)
Quality and protections30%7/105/10
Efficiency20%8/108/10
Cabling and connectors20%8/107/10
Noise15%6/105/10
Warranty15%10/1010/10
Overall7.7/106.8/10

Specifications

SpecCorsair RMx Series RM1000x Fully Modular Power SupplySeasonic FOCUS GX-850 ATX 3 (2024)
Rated output (W)1000W continuous850 W
Efficiency rating (80 Plus or Cybenetics)Measured Cybenetics Platinum: 89-91% at 115V, 91-93% at 230V (Hardware Busters)80 PLUS Gold
Form factor (ATX or SFX) and ATX 3.x / PCIe 5.x supportATX, 160x150x86 mm (Corsair); 150x85x160 mm (Hardware Busters)ATX
Modular cabling (fully, semi or non-modular)Fully modular, Type-4 cablesFully modular
Graphics card connectors (12V-2x6 / 12VHPWR and PCIe 8-pin count)1x PCIe 12V-2x6 (12+4), 4x PCIe 8-pin (6+2), 2x EPS 8-pin, 12x SATA, 6x PATA1x 12V-2x6 (native); 1x PCIe 12+4 pin (600W) per Hardware Busters; 3x PCIe 6+2 pin; 8x SATA; 3x Molex
Fan size and zero-fan mode1x 140mm fluid dynamic bearing fan with Zero RPM mode and manual override knob135 mm fluid dynamic bearing fan; semi-passive mode (selectable)
Warranty (years)10 years10 years

Strengths and weaknesses

Corsair RMx Series RM1000x Fully Modular Power Supply

  • + 10-year warranty
  • + Native 12V-2x6 plus four PCIe 8-pin and 12 SATA
  • + Platinum-level efficiency measured on 230V
  • − Light-load efficiency is modest, about 74% at 20W
  • − Some owners report scratchy fan noise near full speed
  • − Some owners say the fan runs at full speed at desktop

Skip it if:

  • Buyers building a low-power always-on box who want high efficiency at very light loads
  • Buyers who need an utterly silent system and are bothered by reports of fan noise
  • Buyers with a small chassis that cannot take a roughly 160 mm deep ATX unit
Read the full Corsair RMx Series RM1000x Fully Modular Power Supply review ›

Seasonic FOCUS GX-850 ATX 3 (2024)

  • + 10-year warranty, praised by owners
  • + Cybenetics Platinum efficiency despite the Gold label
  • + Fully modular with native 12V-2x6 cable
  • − Loose 12V load regulation per Hardware Busters
  • − Fan curve complaints; spins up early for some owners
  • − Cables reported as bulky or short

Skip it if:

  • Buyers who put tight 12 V voltage regulation first
  • Builders who need a consistently silent fan at low load
  • Anyone with a compact case who needs long, flexible cables
Read the full Seasonic FOCUS GX-850 ATX 3 (2024) review ›

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