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.

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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

Rail 3.3V 5V 12V 5VSB -12V Max. Power Amps 25 25 70.8 3 0.8 Watts 150 850 15 9.6 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

Modular Cables Description Cable Count Connector Count (Total) Gauge In Cable Capacitors ATX connector 20+4 pin (600mm) 1 1 18-20AWG Yes 4+4 pin EPS12V (650mm) 2 2 18AWG Yes 6+2 pin PCIe (600mm+150mm) 3 6 18AWG Yes SATA (500mm+110mm+110mm+110mm) 1 4 18AWG No SATA (520mm+110mm+110mm) 2 6 18AWG No Four-pin Molex (450mm+100mm+100mm+100mm) 2 8 18AWG No FDD Adapter (+100mm) 1 1 20AWG No AC Power Cord (1430mm) - C13 coupler 1 1 16AWG -

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.

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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.

Specifications

Manufacturer (OEM) CWT Max. DC Output 850W Efficiency 80 PLUS Gold, ETA-A Noise LAMBDA-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 ✓ Cooling 135mm Rifle Bearing Fan (NR135L) Semi-Passive Operation ✓ Dimensions (WxHxD) 150 x 86 x 162mm Weight 1.66kg (3.66lb) Form Factor ATX12V v2.4, EPS 2.92 Warranty 10 Years

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