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

  • DanNeely - Tuesday, October 24, 2017 - link

    I think I found an error. The table lists only 1 4+4 pin CPU power cable. Corsair lists 2 (as does newegg). In addition there're 5 12v connector ports on the PSU, 2 CPU and 3 GPU cables would fill this out nicely. And with the proliferation of new high end boards expecting 8+4 or 8+8 CPU power connections only 1 would be a poor fit for the enthusiast market.
  • DanNeely - Tuesday, October 24, 2017 - link

    I also have a question. Do the PCIe cables split into a Y with 2 independent wire bundles at the PSU or are the two connectors daisy chained on a single wire bundle.

    I'm asking because with the proliferation of single 8 pin power connection GPUs the daisy chain topology makes cable management a lot easier since you don't have to hide an entire 18 or 24" wire bundle. Having to do so sorta defeats the purpose of modular design IMO.
  • jonnyGURU - Monday, October 30, 2017 - link

    All of the Corsair PSUs that use Type 3 or Type 4 cables use "pig tail" cables that put two PCIe connectors on one cable.
  • TEAMSWITCHER - Tuesday, October 24, 2017 - link

    That 10 year warranty is a nice feature.
  • Golgatha777 - Tuesday, October 24, 2017 - link

    Hopefully you'll never need it. My HX850 has been going strong through multi-gpu and overclocked CPU setups since Sept 2011. Currently it's got a light load of an overclocked i7-5820k and GTX 1080 ti.
  • DanNeely - Tuesday, October 24, 2017 - link

    Good PSUs tend to be rather reliable so probably not. Over the last 15 years I've gotten about 35-40 years or so of run time over 7 or 8 different PSUs in my personal computers. 0 failures with anything electrical. 1 mechanical fault from a modular connector plug that somehow got smashed back into the body of the PSU and no longer made good electrical contact with the cable plugged into it.

    Attrition in models over the years has been mostly due to changing standards. 3.3/5v vs 12v focused models. Sata plugs instead of molex. The CPU connector going from 4 pins to 8 pins (and to twin connectors whenever I build a new high end box). PCIe power plugs being added, increasing in number and getting 8 pin versions. At the bottom end I think I retired a basic 80+ model after working out that over the boxes lifespan a more efficient one would pay for itself.
  • just4U - Wednesday, October 25, 2017 - link


    Your's was made by Seasonic, CWT has never been quite as good. The warranty is nice though.
  • jonnyGURU - Monday, October 30, 2017 - link

    They leap frog each other. Seasonic stalled for a while, allowing CWT to put out better products for a number of partners. But with the Prime line, Seasonic has jumped back ahead. Still... I'd take a newer CWT over an older Seasonic.
  • StevoLincolnite - Wednesday, October 25, 2017 - link

    Got an almost 12 year old HX620 humming along fine in a Core 2 Quad QX9770 @ 3.8ghz + 8GB DDR2 + Radeon 7970 rig. Still plays the latest games at 1080P every day.

    Only PSU's I will buy are Corsair... Another company would need to prove they have the reliability+features+warranty and beat Corsair on price for me to even remotely consider them.
  • BurntMyBacon - Wednesday, October 25, 2017 - link


    Corsair (HX or AX series only) is one of only three PSU manufacturers I consider for builds as well. I have seen good reliability out of them with their HX and AX series supplies. Judging by your criteria, I propose considering Seasonic for your short list as well. I've installed several of their old X-Series power supplies that are about the same age as your H620 and still going strong. Two of them are 24-7 operators (Folding@home or gaming) with multiple GPUs. The irony is Corsair used Seasonic's platform for a lot of their earlier HX and AX series PSUs so your HX620 may in fact be a Seasonic platform. Their prime series has some of the best performance in the industry (Similar to Corsairs Flextronics based AX1200/AX1500) and they come with a 12 year warranty. About the only thing missing (for those who can use it) is a Corsair Link equivalent. Pricing is competitive with Corsairs HX and AX series supplies and the better deal usually comes down to which one is on sale.

    Warranty Upgrade:

    Article to check it out:

Log in

Don't have an account? Sign up now