Box & Bundle
The box has a photo of the PSU on its front side and the corresponding Cybenetics ratings for efficiency and noise. If you want more data about the PSU’s technical specs, look at the back of the box.
Product Photos
The chassis has a distinct look, with the uniquely shaped perforations that Corsair used for the fan and exhaust grilles. Moreover, the PSU has standard dimensions, allowing for a 140mm fan to offer the desired airflow at low enough RPMs for reduced noise output. On the front side, you will find the power switch, the AC receptacle, and the fan speed control knob. Around the back, the modular board has 14x sockets, one of which is 12V-2×6 type. Corsair didn’t use 2x 8-pin sockets in these PSUs for the high-power PCIe connector, but preferred a native one.
Cables
| Modular Cables | ||||
| Description | Cable Count | Connector Count (Total) | Gauge | In Cable Capacitors |
|---|---|---|---|---|
| ATX connector 20+4 pin (610mm) | 1 | 1 | 16-20AWG | No |
| 4+4 pin EPS12V (750mm) | 2 | 2 | 18AWG | No |
| 6+2 pin PCIe (650mm) | 3 | 3 | 16-18AWG | No |
| 12+2 pin PCIe (650mm) (600W) | 1 | 1 | 16-24AWG | No |
| SATA (500mm+115mm+115mm+115mm) | 2 | 8 | 18AWG | No |
| 4-pin Molex (550mm+100mm+100mm) | 1 | 3 | 18AWG | No |
| AC Power Cord (1400mm) – C13 coupler | 1 | 1 | 18AWG | – |
All cables are embossed, and the PSU has two EPS and three PCIe 6+2 pin connectors, all on dedicated cables, which is the correct/best thing to do. There is also a high-power PCIe connector, set at 600W max power. There are enough cables and connectors to allow the PSU to deliver its full power without any issues, and all cables are long enough to avoid compatibility issues. I only disagree with the short distances between the peripheral connectors.
I had coil whine in my RM850x. It was quite noticeable during idle, so I returned it.
Would be interesting to know what percentage of these PSUs have coil whine.
Hi, what is that knob for? If I turn it to the right, I hear a loud fan sound, if I turn it to the left, I don’t hear the fan sound, but I hear a DIDA sound. Is this to turn off the fan? My power supply is RM1000X.
it sets the minimum fan speed
Hello Aris, can you tell, what is the minimal fan speed to set via fan knob? Is it still quiet? As I found out, Corsair set minimal fan speed in their PSu to +/- 40%. Thank you for the answer.
I don’t remember to be frank, but I don’t believe that Corsair would have loud the minimal fan setting on this unit. They use PWM fans which can go very low in speeds without any probs.
Hola aris, soy de colombia estoy entre Corsair RM850x ATX v3.1 $169 vs nzxt c1000 gold $164 cual me recomiendas
Hi! I would go for the C1000 most likely because of the 150W more.
Hello aris , about the inrush current of CORSAIR RM850x , it was very low according to your observation and you were not able to get meaningful readings , can you explain this in detail , i know that the inrush current should be as low as possible , waiting for your reply .
thanks
Hi! In some PSUs, the NTC thermistor does an excellent job of restricting inrush currents, so we don’t have a solid reading to present. This is a rare case, but it happens.
thanks for replying Aris , you are doing great job with detailed analysis of PSU , it is really helping me in selecting proper PSU, i will go for CORSAIR RM850x , if you have any suggestion it will be really helpful .
Hi Aris. What better Corsair RM850x or Asus rog strix platinum 850W? Corsair cost 170$, Asus 198$. Thanks!
I would go for the Corsair RM850x (ATX v3.1)
Hi Aris,
I’m going to buy a Corsair rm850x but you don’t have an Amazon link to it. Do you still get credit if I hit their site through your link to another product and browse for what I want?
Thanks for all your work. It’s PLENTY worth supporting. Put up a sponsorship link, as well!
Thank you Alan! Here is the link https://amzn.to/4hiXEHu
man did you buy it? How’s it going today? I’m looking forward to buying it, but I can’t decide.
It is a review sample so I only used for the review.
Thank you for the review, Aris. I can’t decide which PSU to buy, the Corsair RM850x (2024) or the Super Flower Leadex VII XG 850W. They are both at the same price in my country. Which one do you think is the better one and you would take?
Another hardware site, LTT, mentions that the previous version doesn’t have UVP but instead “CFP”? Corsair mentions this has UVP (as required by ATX specification), and I was wondering if you test for that?
don’t follow what LTT says, sorry. I can only know what I do in my lab.
This PSU was the worst I’ve bought over 20 years of building PC’s every few years. The cables smelled of cheap plastic, and the unit itself let off a nasty burnt cable smell, neither of which dissipated away after running it for 3 days under a ventilator. Sent it back to the shop, hopefully getting a refund. Not buying corsair PSU’s anymore for a long time.
Weird, we didn’t notice this smell, which might exist indeed in some PSUs.
I sent it for RMA, they replaced it, just now opened the replacement box, the same nasty smell is on the cables on a brand new unit. Won’t even bother installing it, this time will make sure to ask for a refund.
Hey Aris, thank you for the review. After my long research and your articles, I finally bought this product (it finally arrived in my country). Is it a problem if the 3.3V channel drops below 3.2? If it is a problem, what causes it?
weirdingly enough, I just noticed this post. 3.3V rail is not used so hard anymore.