Researched, not hands-on tested.How we review ›
all judged against power supplies at a similar priceThe be quiet! Pure Power 12 M 850W and Corsair RMx Series RM1000x Fully Modular Power Supply both score 7.7/10 overall.
The be quiet! Pure Power 12 M 850W leads on noise.
The Corsair RMx Series RM1000x Fully Modular Power Supply leads on efficiency.
They score the same on quality and protections, cabling and connectors and warranty.
This is an 850 W fully modular ATX 3.0 power supply for builders who want a quiet PC with a modern GPU connector. It suits gaming and general-purpose desktops that will rarely sit near full load. It is a weaker fit for anyone who wants a fan that stops entirely at idle.
Search Amazon UK (opens in a new tab, affiliate link)Affiliate link. As an Amazon Associate I earn from qualifying purchases. Details
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
| Criterion | Weight | be quiet! Pure Power 12 M 850W | Corsair RMx Series RM1000x Fully Modular Power Supply |
|---|---|---|---|
| Quality and protections | 30% | 7/10 | 7/10 |
| Efficiency | 20% | 7/10 | 8/10 |
| Cabling and connectors | 20% | 8/10 | 8/10 |
| Noise | 15% | 7/10 | 6/10 |
| Warranty | 15% | 10/10 | 10/10 |
| Overall | 7.7/10 | 7.7/10 |
| Spec | be quiet! Pure Power 12 M 850W | Corsair RMx Series RM1000x Fully Modular Power Supply |
|---|---|---|
| Rated output (W) | 850 W continuous, 900 W peak; 850 W combined 12V output, 600 W combined 12VHPWR | 1000W continuous |
| Efficiency rating (80 Plus or Cybenetics) | 80 PLUS Gold; up to 93.2% (manufacturer); Cybenetics [115V] Platinum rating, 89–91% | Measured Cybenetics Platinum: 89-91% at 115V, 91-93% at 230V (Hardware Busters) |
| Form factor (ATX or SFX) and ATX 3.x / PCIe 5.x support | ATX 3.0; PCIe 5.1 compatible | ATX, 160x150x86 mm (Corsair); 150x85x160 mm (Hardware Busters) |
| Modular cabling (fully, semi or non-modular) | Fully modular | Fully modular, Type-4 cables |
| Graphics card connectors (12V-2x6 / 12VHPWR and PCIe 8-pin count) | One 12VHPWR (600 W); four PCIe 6+2-pin; one P8 and one P4+4 CPU; six SATA; two PATA | 1x PCIe 12V-2x6 (12+4), 4x PCIe 8-pin (6+2), 2x EPS 8-pin, 12x SATA, 6x PATA |
| Fan size and zero-fan mode | One 120 mm rifle bearing fan, max 2000 rpm; no zero-fan mode | 1x 140mm fluid dynamic bearing fan with Zero RPM mode and manual override knob |
| Warranty (years) | 10 years | 10 years |
Skip it if:
Skip it if: