Researched, not hands-on tested.How we review ›
all judged against power supplies at a similar priceThe Corsair RM1000x SHIFT (2025) scores 7.8/10 overall, ahead of the be quiet! Pure Power 12 M 850W at 7.7/10.
The Corsair RM1000x SHIFT (2025) leads on noise.
They score the same on quality and protections, efficiency, 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.
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The RM1000x SHIFT (2025) suits builders putting together a high-end gaming or workstation PC with a current NVIDIA card. It offers 1000W, a native 12V-2x6 cable and a side-mounted modular connector layout. It fits people who want a quiet, long-warranty supply and have case space for the side connectors.
Typically about £129.99 in the UK when we researched itCheck price at 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 RM1000x SHIFT (2025) |
|---|---|---|---|
| Quality and protections | 30% | 7/10 | 7/10 |
| Efficiency | 20% | 7/10 | 7/10 |
| Cabling and connectors | 20% | 8/10 | 8/10 |
| Noise | 15% | 7/10 | 8/10 |
| Warranty | 15% | 10/10 | 10/10 |
| Overall | 7.7/10 | 7.8/10 |
| Spec | be quiet! Pure Power 12 M 850W | Corsair RM1000x SHIFT (2025) |
|---|---|---|
| Rated output (W) | 850 W continuous, 900 W peak; 850 W combined 12V output, 600 W combined 12VHPWR | 1000W combined (+12V 83.3A, 1000W total) |
| Efficiency | 80 PLUS Gold; up to 93.2% (manufacturer); Cybenetics [115V] Platinum rating, 89–91% | Cybenetics Gold |
| Form factor | ATX 3.0; PCIe 5.1 compatible | ATX, ATX 3.1 certified, PCIe 5.1 compliant |
| Cabling | Fully modular | Fully modular |
| GPU power | One 12VHPWR (600 W); four PCIe 6+2-pin; one P8 and one P4+4 CPU; six SATA; two PATA | One native 12V-2x6 cable; PCIe 8-pin counts differ by source; SATA 12 (Tech2Geek) or 16 (Corsair white SKU page) |
| Fan size and zero-fan mode | One 120 mm rifle bearing fan, max 2000 rpm; no zero-fan mode | 140mm fluid dynamic bearing fan, model NR140HP, with Zero RPM mode |
| Warranty (years) | 10 years | 10 years |
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