Conclusion

Corsair is aiming the entirety of the HX series, including the HX850 that we reviewed today, towards overclockers and advanced enthusiasts. These groups of users primarily value reliability and stability, but also need high overall performance, and are usually not dissuaded by a hefty price tag. The HX units are designed around that concept - the platform is primarily focused around the longevity of the PSU above everything else but without forgoing other performance aspects.

The overall electrical performance of the Corsair HX850 is exceptional. Even with the PSU heavily loaded under adverse operating conditions, the power quality readings that we took were excellent, with minimal voltage ripple appearing on all of the voltage lines and very strong regulation. Our readings were impressive but not unexpected of a high-quality modern PSU. The HX850 is not going to break any performance records here but pinnacle electrical performance is not the purpose of this series - Corsair has the AX series for that.

Our sample did not fully meet the 80Plus Platinum certification with an input voltage of 230V/50Hz, failing to surpass 94% efficiency at 50% load. As most companies do, Corsair is having their units tested and certified for an input voltage of 115V/60Hz and this specific unit has been officially tested and awarded an 80Plus Platinum certification, so there is nothing suspicious going on here. Apparently, the company’s engineers optimized the platform for an input voltage of 115V, as the lower requirements make it easier to achieve a better efficiency certification. Regardless of that, the conversion efficiency of the HX850 can definitely be characterized as excellent, with our sample sustaining an average efficiency of 92.7% across its nominal load range.

Although we feel that its heatsinks and overall thermal design could use an improvement, the high efficiency allows the Corsair HX850 to display very good thermal performance - perhaps even a little too good. The thermal control is very sensitive when the internal temperatures of the unit are high, pushing the 135 mm fan to its limit in order to keep the internal temperatures as low as possible. With the maximization of the unit’s reliability and stability being the primary design focus, that is not surprising, as even a few temperature degrees can mean years of difference on the lifetime of some electronic components, especially that of capacitors. The downside here is that the HX850 can become quite loud when forced to operate inside a very hot ambient environment.

At room temperature, the thermal behavior of the HX850 is entirely different, with the unit’s thermal control not even turning the fan on up until the load reaches almost half of the unit’s rated capacity.

The retail price of the Corsair HX850 currently is $160 (MSRP $200), which is a fair price for a high quality 80Plus Platinum certified unit that comes with a 10-year warranty. 80Plus Platinum units can nowadays found for less but most manufacturers have their leading designs priced around this price point and the HX850 is more than capable of giving the competition a run for their money.

The Corsair HX850 should be into the shortlist of anyone seeking a powerful, efficient, and very reliable PSU that will be the heart of their gaming/workstation system for many years.

Recent Power Supply Reviews

AnandTech tests a good number of power supplies each year, mostly in the popular power ranges (650-850W) with a few reviews now-and-again for small form factor parts or larger behemoths. Here are the power supplies we have reviewed in the last twelve to eighteen months.

  • [link] The Corsair HX850 80Plus Platinum PSU Review (this review)
  • [link] The Enermax Revolution SFX 650W PSU Review
  • [link] The Seasonic PRIME Titanium PSU (650W, 750W, 850W) Review
  • [link] The Riotoro Onyx Power Supply Review: 650W & 750W Tested
  • [link] The BitFenix Whisper M 450W & 850W PSU Review
  • [link] The Silverstone ST30SF & ST45SF SFX Power Supply Review
  • [link] The Zalman ZM1200-EBT 1200W Power Supply Review
  • [link] The SilverStone SX700-LPT SFX 700W PSU Review
Hot Box Test Results
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  • 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.

    http://www.corsair.com/en-us/hx-series-hx850-850-w...
  • 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

    G..

    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

    @StevoLincolnite

    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:
    https://seasonic.com/seasonic-upgrades-prime-serie...

    Article to check it out:
    https://www.hardocp.com/article/2016/07/21/seasoni...

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