Corsair may today be one of the largest companies in the PC market, offering literally hundreds of products, but that was not always the case. The company started off as a manufacturer of memory-related computer products and took them many years to even consider diversifying into other segments of the market. Their first significant diversification attempt away from RAM-related products was towards the power supply unit (PSU) market, with the company initially releasing just a couple of PSUs. That move was a great success for the company and the beginning of Corsair's expansion towards multiple segments of the PC market.

Although the company today produces hundreds of products, they still place a significant amount of attention on their power supply products, with Corsair having not only one of the largest selection of products but excellent reputation in the field as well. The company today markets dozens of PSUs through nine different product series. In today's review, we are testing a unit of their most popular series, the RMx.

Corsair initially released the RM series several years ago, with the products designed to be reliable, quiet, and to offer good overall performance, yet still affordable. More recently, the company added some new features that bifurcated the series in two, giving birth to the RMi and RMx series. With the former, Corsair added software monitoring and control to the RM series, a feature that was previously reserved only for the premium HXi and AXi units, however the added features did come at the cost of higher prices. On the other hand, the RMx series is true to the original vision of the family, consisting of quality modular PSUs that are primarily designed to offer good overall performance and quiet operation. The unit that we are reviewing today is the latest (2018) revision of the RM850x.

Power specifications ( Rated @ 50 °C )
AC INPUT 100 - 240 VAC, 50 - 60 Hz
RAIL +3.3V +5V +12V +5Vsb -12V
MAX OUTPUT 25A 25A 70.8A 3A 0.8A
150W 850W 15W 9.6W

Packaging and Bundle

We received the RM850x in a large cardboard box with the yellow-black artwork that is becoming the company's color theme. The front of the packaging is clean, focused on a picture of the unit itself and noting its output and only the most important features. Detailed information about the unit and its performance can be found on the sides and rear of the box. Inside the box we found the PSU protected inside thick foam paddings and packed inside a synthetic cloth pouch.

The bundle of the RM850x is simple and straightforward, which is not something unexpected for a product of this class. We received a typical AC power cable, four black M3.5 mounting screws, a thorough manual that is printed in 10 languages, a case badge and a few short cable ties. Corsair does not include thumbscrews, cable straps, or other accessories with this PSU.

Like its previous version, the RM850x is fully modular, meaning that even the always-necessary 24-pin ATX cable is removable. The SATA and Molex cables are flat, ribbon-like, but the larger PCIe and ATX/EPS power cables are normal round cables with black nylon sleeving. The designer could not use ribbon-like wires for everything because small filtering capacitors are hidden inside the sleeving of the larger cables. The cables are supplied inside a nylon storage pouch. No cable straps are supplied here either, Corsair is using simple wire ties.

Corsair RM850x (2018)
Connector type Hardwired Modular
ATX 24 Pin - 1
EPS 4+4 Pin - 2
EPS 8 Pin - -
PCI-E 6+2 Pin - 6
PCI-E 8 Pin - -
SATA - 10
Molex - 8
Floppy - 1
The Corsair RM850x (2018) PSU
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  • austinsguitar - Wednesday, August 22, 2018 - link

    picked this thing up for 99 dollars last week at best buy. Super quiet most of the time. Love it... capacitors in the wires are huge...
  • Cellar Door - Wednesday, August 22, 2018 - link

    It would cost Corsair less then $0.50 to include a ball bearing version o the fan.
  • philehidiot - Thursday, August 23, 2018 - link

    Do remember volume. That $0.50 might do a couple of things. Firstly when multiplied by a lot of units that becomes $0.50 x lots. Which is (($0.50)lots). Which is a lot. The other issue is if you push that onto the consumer then it may send the price over a psychological threshold which has been shown to lead to reduced overall sales. Whilst the individual is rational and when informed would rather spend $0.50 for the nice fan, the herd acts like a bunch of morons who need to be carefully led.

    This presents a problem because cows are stupid, but you want their milk.
  • Cellar Door - Thursday, August 23, 2018 - link

    Terrible analysis - higher volume means lower overall costs. As Corsair already uses higher quality fans in other units.
  • philehidiot - Wednesday, June 30, 2021 - link

    My comeback is a few years late. But you can only reduce costs with economies of scale so far. Some parts are fundamentally more expensive and the producers still need to make a profit. Last company I saw focus purely on volume, relying on economies of scale, went very bust very quickly. As I said, it might be that psychological threshold or just plain budget that they have to keep under. The other models might have had room in the budget for the ball bearing fan. Or, quite possibly, the market for power supplies of this level just doesn't use the fan type as a discriminator. They use ripple, efficiency and so on.

    I trust that you won't be coming back to this several years down the line and shall therefore assume I win the argument. Victory!
  • austinsguitar - Saturday, August 25, 2018 - link

    the fan is ball bearing?
  • Batmeat - Wednesday, August 22, 2018 - link

    Third paragraph had the word "bifurcated" in it back to back.
  • Ryan Smith - Wednesday, August 22, 2018 - link

  • mgabee - Thursday, August 23, 2018 - link

    Best PSU, beside the EVGA G3 series of course. Jonnyguru makes Corsair PSUs more brilliant with this 2018 upgrade. I have the RM550x: the quality is insane, deadly silent, Vcore drop halved under load. It is definitely a 10yr long PSU with the best price/performance ratio.
  • IgorM - Thursday, August 23, 2018 - link

    I must disagree with crypto mining part. We have at least 3 Rmx 850 and at least 20 Rmx 1000 working almost a year with pretty harsh conditions, up to 43 C in the room, almost full load, and none died yet and works excellent. We also have LC power PSUs, because supply of Corsair was limited at the time, and they are dying often.

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