Corsair RM850x V2 PSU Review: Smaller And Quieter!

Tom's Hardware Verdict

The RM850x V2 is more compact than its predecessor, yet still offers great performance. At the same time, it's one of the quietest 850W PSUs you can buy and backed by a 10-year warranty. If you want a rock-solid and near-silent PSU, this one should be on your short list.


  • +

    Full power at 47°C

  • +

    Quiet across its operating range

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    Solid build quality

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    Fully modular

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    2x EPS & 6x PCIe connectors

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    Compact dimensions

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    10-year warranty


  • -

    In-cable caps

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    Short distance between peripheral connectors

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    No fan-test button

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Features & Specifications

Corsair is a key player in the PSU market, battling EVGA for first place in U.S. sales. One of the company's most recognizable and popular power supply families is the RMx, with all of its models offering plenty of value and quiet operation. The RMx line-up has already been around for more than three years though, and given EVGA's newer G3 series, it was time for Corsair to strike back.

It seems like Corsair prefers to upgrade its PSUs quietly, implementing improvements without model number modifications. That's why the revised RMx units are named like their predecessors. We add the "V2" for purposes of differentiation.

At least for now, there are four new RMx models with capacities ranging from 550W to 850W. The biggest differences are apparent on the two higher-capacity PSUs, which are 20mm shorter than they were before. This makes them easier to install, particularly in smaller cases. Another notable addition is the RM750x V2's second EPS connector. The previous-gen version only had one. And in our opinion, the RM650x should have two EPS connectors as well. The RM850x V2 we're evaluating today costs $120 and offers exceptional performance, plus ultra-quiet operation.

Since the RM850x is the V2 family's current flagship, that's the model we'll review first. It's manufactured by Channel Well Technology, and we see no reason for Corsair to look elsewhere since CWT does such a good job. With that said, we're sure many enthusiasts would be happy to see the OEM refresh this platform's aesthetics, if only because the current design is starting to look a bit dated.

The RM850x V2 features 80 PLUS Gold and ETA-A efficiency certifications, along with Cybenetics' LAMBDA-A+ noise rating. On paper, those are identical to Corsair's previous-generation RM850x. But the V2 model does output around 3 dB(A) less noise overall. This is because the original RM850x landed right on the line between LAMBDA-A+ and LAMBDA-A, while the RM850x V2 is close to the lower threshold of LAMBDA-A+.

As we'd expect, all necessary protection features are present. Moreover, the RM850x V2's maximum operating temperature for continuous full load operation is set at 50°C, per the ATX specification's recommendation.

When it comes to cooling, we find the same fan used on previous-generation models. The NR135L uses a rifle bearing, which is an enhanced version of the sleeve bearing that costs less than higher-end FDB/HDB-based solutions.

Power Specifications

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Max. PowerAmps252570.830.8
Total Max. Power (W)850

The minor rails are overkill by today's standards, given their 150W maximum combined power. Fortunately, the +12V rail, which is what matters most in a modern PSU, can deliver the RM850x V2's full capacity on its own. Finally, the 5VSB rail offers 3A maximum current output.

Cables & Connectors

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Modular Cables
DescriptionCable CountConnector Count (Total)GaugeIn Cable Capacitors
ATX connector 20+4 pin (600mm)1118-20AWGYes
4+4 pin EPS12V (650mm)2218AWGYes
6+2 pin PCIe (600mm+150mm) 3618AWGYes
SATA (500mm+110mm+110mm+110mm)1418AWGNo
SATA (520mm+110mm+110mm)2618AWGNo
Four-pin Molex (450mm+100mm+100mm+100mm)2818AWGNo
FDD Adapter (+100mm)1120AWGNo
AC Power Cord (1430mm) - C13 coupler1116AWG-

Corsair gives us two EPS connectors and six PCIe ones. That's enough to support a potent workstation with a high-end CPU and multiple graphics cards.

Peripheral connectivity is copious as well. We don't usually encounter eight four-pin Molex connectors, even in larger-capacity PSUs. Although the distance between PCIe connectors is good, we can't say the same for the peripheral connectors. A mere 10-11cm between them isn't enough in many enclosures. Usually, components fed by four-pin Molex connectors (like case fans) are installed far away from each other. The same goes for some hard drives and SSDs. That's why we want to see at least 15cm between all peripheral connectors.

The RM850 V2's cables are shown in the photos above.

Power Distribution

Since this PSU features a single +12V rail, we do not have anything to say about its power distribution.


Swipe to scroll horizontally
Manufacturer (OEM)CWT
Max. DC Output850W
Efficiency80 PLUS Gold, ETA-A
Modular✓ (Fully)
Intel C6/C7 Power State Support
Operating Temperature (Continuous Full Load)0 - 50°C
Over Voltage Protection
Under Voltage Protection
Over Power Protection
Over Current (+12V) Protection
Over Temperature Protection
Short Circuit Protection
Surge Protection
Inrush Current Protection
Fan Failure Protection
No Load Operation
Cooling135mm Rifle Bearing Fan (NR135L)
Semi-Passive Operation
Dimensions (WxHxD)150 x 86 x 162mm
Weight1.66kg (3.66lb)
Form FactorATX12V v2.4, EPS 2.92
Warranty10 Years

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Contributing Editor

Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.

  • parkerygc8
    Sweet, first review of this I've seen. Thanks.
  • leclod
    I didn't go into detail, but I wonder what's the use of that Gold PSU when there's a Seasonic Focus Plus Platinum 750 for a similar price ?
  • Aris_Mp
    Gold, Platinum, it doesn't really matter at this efficiency point. What matters the most, in my opinion at least, is noise output now besides the basic (reliability and overall performance).
  • powernod
    At last some scoring at the review conclusion!! I always considered the lack of score as Tom's greater weakness about their reviews !!