The Corsair HX850 80Plus Platinum PSU

External Appearance

The core aesthetic design of the Corsair HX850 is the same that the company has been using for years for their high-end units. It features a classy, understated design, with a satin black body and all-black cables. The chassis has chamfered edges and decorative stickers cover the largest portion of its sides. Further aesthetic improvements include embossed parallel ridges aligned with the fan’s finger guard wires and a small badge with the unit’s model at the rear side of the chassis. The chassis of the HX850 is 180 mm long, making it significantly longer than a standard ATX unit. This should not be a problem with any modern high-performance ATX case but caution is required with compact and atypical case designs.


Corsair moved the sticker with the unit’s specifications and certifications to the top of the chassis, allowing the user to hide it when the unit is installed with the cooling fan facing upwards. The side stickers are also installed in such a way so that the sticker facing the left panel of the case will always be upright. However, the sticker facing the right panel will always be upside down. Typical cases very rarely have a transparent right side panel but this could be a problem for custom designs. Still, a modder technically can remove and reinstall the side stickers without voiding the unit’s warranty, although keeping the sticker in pristine condition while removing it could prove to be a challenge.


The front of the chassis is littered with the connectors for the modular cables. Aside from the split 18+10 connectors for the 24-pin ATX cable, the rest of the connectors are essentially split into two groups: one group of five PCIe and CPU power connectors and one group of six SATA/Molex connectors. The PCIe and CPU cables share the same connectors on the side of the PSU. There is also a button that allows the user to switch from a single 12V rail mode to a multiple (seven) rail mode. When in multiple rail mode, the HX850 splits the 70.8A 12V output into seven virtual 40A lines, triggering an over-current protection shutdown if a single virtual line is overloaded. This mode provides additional safety and should be used by default, leaving the single rail mode only for competition overclockers or other special applications where a single device could momentarily require over 480 Watts and trigger a safety shutdown.

Packaging and Bundle

Corsair ships the HX850 in a large cardboard box with yellow/black artwork, which is becoming the company’s packaging insignia. The artwork is clean, with the front mainly focused on a picture of the unit itself and a lot of information printed on the sides and rear of the box. Inside the strong cardboard box, we found the unit well protected between thick foam paddings.

Strangely, the bundle of the HX850 is relatively frugal for a PSU of this class. Corsair supplies only the typical AC power cable, black 3M mounting screws, a very thorough multilingual manual, a case badge and a few short cable ties. There are no thumbscrews, cable straps, or other accessories.

The latest version of the HX850 is fully modular, allowing the user to remove even the 24-pin ATX cable. 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 cables are supplied inside a nylon storage pouch. 

Corsair HX850 (CP-9020138)
Connector type Hardwired Modular
ATX 24 Pin - 1
EPS 4+4 Pin - 1
EPS 8 Pin - -
PCI-E 6+2 Pin - 6
PCI-E 8 Pin - -
SATA - 16
Molex - 6
Floppy - 1


Introduction, Internal Inspection Cold Test Results (Room Temperature)
Comments Locked


View All Comments

  • BurntMyBacon - Wednesday, October 25, 2017 - link

    I should probably mention that there are a few different versions of prime supply differentiated by efficiency:



  • evilspoons - Tuesday, October 24, 2017 - link

    As a Canadian who has to translate from USD to CAD all the time mentally, I'm always surprised when I find out you review your power supplies at 230V/50Hz (i.e. not in North America). I guess you get to do that bit of mental translation too.

    Good to know the Corsair supplies are still solid. I've had an HX750 since I bought my i7-2600k and it ran SLI 680s and an overclocked CPU since whenever that was. The 680s have since been replaced with a 1080 but if I ever need a PSU, shouldn't be too hard to choose...
  • Morawka - Tuesday, October 24, 2017 - link

    It's funny how we've come full circle with power supplies. At first a Single 12V rail was desirable but nowadays, a Multiple rail system is preferred with the advent of virtual rails. I have a question. I have a RMI 1000x PSU from Corsair which also has Single and Multi-rail options. So is it generally preferred to keep it operating in multi-rail mode? Could a single 1080Ti or a 7900X CPU OC'd for example -- go over the 40A rating. (I think the RMi1000 has the same multi-rail setup as this one, albiet more rails.)
  • TheWereCat - Tuesday, October 24, 2017 - link

    1080ti can go easily to 40A when you unlock the power and voltage limit. Not by default as most if not all cards have power limit at around 355W.
    I flashed my FTW3 with XOC BIOS and I am easily hitting 400W (I am using the FTW3 air cooler) so I don't dare to push the card more even if I could but then the very high temps would lower my clocks significantly so it would be pointless.
  • DanNeely - Tuesday, October 24, 2017 - link

    Yup. We started with multiple rails due to a max current safety requirement. Then PSU makers started ignoring that limit and making single giant rails. The standard was updated to allow this. (Were any compensatory safety requirements added?) The safety benefits from smaller overcurrent limits never went away though, so now we're seeing them added back to individual outputs.

    It'll be interesting to see if the PSUs that have an internal USB2 header cable and a control app let you customize the max for each output port separately instead of being a single all or nothing option.
  • Morawka - Tuesday, October 24, 2017 - link

    I'll let you known if that's possible here in a couple of days as i'm building a 7900x with a RM1000i Power supply w/ Corsair Link. Being able to set the max amperage per 12v rail would be ideal for enthusiast.
  • jonnyGURU - Monday, October 30, 2017 - link

    To clarify.. we started with multiple +12V rails until PC Power & Cooling, at the time one of the largest PSU vendors, screwed up and didn't split rails up accordingly for their Turbo-Cool line. Instead of correcting the issue, they went rogue and said "screw this rail B.S.! Make everything single +12V rail!!!" Because their marketing was so strong, they brainwashed everyone into believing that the mistake wasn't on their end and so all the other vendors had to switch to single +12V rail as well to maintain their market share.
  • FaaR - Wednesday, November 1, 2017 - link

    I think you'd have to work hard to make a single GPU pull over 480W of power (;P), but if this worries you, just attach two power cables from different (virtual) rails for a total of 80 amps DC to your GPU.

    Of course, an 850W PSU isn't going to be able to supply that much juice just to your GPU, but you knew that already of course. :)
  • gammaray - Tuesday, October 24, 2017 - link

    so if the HX serie is for "overclockers and advanced enthusiasts" what is the AX and RM series for?
  • Morawka - Tuesday, October 24, 2017 - link

    Corsair Link seems to be the separating feature. Well that and type 4 PSU cables that reduce voltage droop by implementing capacitors along each 12v wire. The RM series are mostly Gold certified whereas the AX series utilizes platinum efficiency with a Digital switching controller (also missing from the TX line)

Log in

Don't have an account? Sign up now