Output and Ripple Results

As it can be seen in the following tables, the electrical performance of the Corsair HX850 is outstanding even when subjected to high ambient temperatures. Our instruments recorded a maximum ripple of 28 mV on the 12V line under maximum load, an exceptional power quality figure for line outputting more than 63 amperes at the time.

Main Output
Load (Watts) 171.81 W 427.92 W 637.89 W 849.49 W
Load (Percent) 20.21% 50.34% 75.05% 99.94%
  Amperes Volts Amperes Volts Amperes Volts Amperes Volts
3.3 V 2.23 3.34 5.57 3.33 8.36 3.31 11.14 3.3
5 V 2.23 5.06 5.57 5.05 8.36 5.04 11.14 5.02
12 V 12.62 12.13 31.56 12.08 47.34 12 63.12 11.99

The maximum ripple recorded on the 3.3V and 5V lines did not exceed 20 mV under normal load distribution and was only slightly higher with the HX850 heavily cross-loaded. 

Line Regulation
(20% to 100% load)
Voltage Ripple (mV)
20% Load 50% Load 75% Load 100% Load CL1
3.3V + 5V
3.3V 1% 10 14 16 16 10 22
5V 0.9% 10 16 16 20 12 24
12V 1.2% 12 16 20 28 32 18

The voltage regulation is exceptional as well, with the 12V line staying within 1.2% across the nominal load range and the 3.3V/5V lines falling below 1%.

Hot Box Test Results

The impact that high ambient temperature has on the electrical performance of the Corsair HX850 is measurable but, considering the output of the unit and its thermal design, is relatively small.

The drop is almost linear across the entire load range, meaning that no components appear to be getting thermally overstressed at higher loads. The average nominal load (20-100%) efficiency dropped down to 91.2% during this test, but with an ambient temperature well above 45 °C.

Testing the Corsair HX850 inside our hotbox changes its thermal profile almost completely. The fan started almost right away this time and its speed was constantly increasing alongside with the load. From the relatively low internal temperature of the unit under these conditions, it appears that the cooling profile of the HX850 is aggressive, sacrificing comfort for safety. The unit will be intolerably loud when heavily loaded under such conditions but Corsair ensured that it will keep operating seamlessly and reliably, with its internal temperatures well within safety levels.

Cold Test Results (Room Temperature) Final Words & Conclusion


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. Reply
  • TEAMSWITCHER - Tuesday, October 24, 2017 - link

    That 10 year warranty is a nice feature. Reply
  • 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. Reply
  • 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. Reply
  • 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:

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