Corsair CS850M 850W Power Supply Review

Load Regulation, Hold-Up Time And Inrush Current

To read about our PSU tests in-depth, please check out How We Test Power Supply Units.

Primary Rails And 5VSB Load Regulation

The following charts show the voltage values of the main rails, recorded over a range from 40W to the maximum specified load, and the deviation (in percent) for the same load range. You will also find a chart showing how the 5VSB rail deals with the load we throw at it.

Load Regulation testing is detailed here.


Hold-Up Time

Our hold-up time tests are described in detail here.


In this screenshot, the blue line is the mains signal and the yellow line is the “Power Good” signal. The hold-up time that our equipment measured is lower than the minimum allowed, so the PSU fails the test. Corsair should use larger APFC capacitors to achieve over 16ms hold-up time. They're not cheap though, and they have a negative effect on efficiency.

Inrush Current

For details on our inrush current testing, please click here.


Although Corsair went with smaller capacitors in the APFC converter, the registered inrush current of 230VAC is pretty high. This indicates that a larger NTC thermistor should be used.

Load Regulation And Efficiency Measurements

The first set of tests reveals the stability of the voltage rails and the PSU's efficiency. The applied load equals (approximately) 10 percent to 105 percent of the maximum load the supply can handle, in increments of 10 percentage points.

We conduct two additional tests. In the first metric, we stress the two minor rails (5V and 3.3V) with a high load while the load at +12V is only 0.10A. This test reveals whether the PSU is Haswell-ready or not. In the second test, we determine the maximum load the +12V rail can handle while the load on the minor rails was minimal.

Test12V (A/V)
5V (A/V)
3.3V (A/V)
5VSB (A/V)
Power
DC/AC (W)
Efficiency (%)
Fan Speed (RPM)
Noise dB(A)
In/Out (°C)PF/AC
(V)

1

5.1921.9721.9740.99084.7484.9986034.037.510.962
12.1715.0623.3405.02699.7140.65115.1

2

11.4222.9622.9651.196169.6589.4690834.838.150.973
12.1535.0503.3355.008189.6341.64115.0
3
18.0223.4753.4811.400254.8290.5697836.239.500.983
12.1375.0403.3294.992281.3743.44114.9
424.6323.9713.9701.605339.7290.75107339.240.370.988
12.1215.0303.3234.975374.3545.05114.8
530.9094.9764.9721.813424.6090.41117942.641.950.991
12.1055.0183.3174.958469.6647.37114.8
637.2105.9915.9752.020509.6389.83128044.342.370.993
12.0905.0063.3124.940567.3248.99114.7
743.5297.0086.9832.232594.5789.10139045.943.390.995
12.0734.9913.3064.922667.3450.96114.6
849.8628.0348.0062.445679.4688.27148346.644.160.995
12.0554.9783.2974.902769.7552.73114.5
956.6538.5528.5452.450764.5687.45159548.444.960.996
12.0384.9683.2884.893874.3054.85114.4
1063.1989.0739.0583.086849.3186.40167549.346.520.996
12.0204.9573.2794.857983.0557.83114.3
1170.3579.0869.0843.091934.2785.33167549.348.240.997
12.0054.9493.2684.8481094.9062.04114.2
CL10.09716.01616.0030.001133.9383.04119142.843.670.971
12.1644.9793.3125.033161.2949.60115.0
CL270.7891.0021.0031.002864.0986.89167549.346.960.996
12.0195.0013.2834.962994.5058.44114.3

For an affordable PSU, load regulation is satisfactory. After all, the CS850M's main purpose is to offer decent performance at the lowest possible cost. On top of that, it manages to deliver full power for quite a while at high operating temperatures, proving that it can handle lots of heat in unfavorable environments. Still, we'd advise you to not operate the CS850M at high ambient temperatures for long if you want to keep it healthy.

As far as efficiency goes, the PSU easily clears the 80 PLUS Gold requirements at 20 and 50 percent of its maximum capacity, but it doesn't manage to sustain 87 percent under full load. Then again, we run our tests at high ambient temperatures, while the 80 PLUS organization uses an unrealistically-low 23 °C, resulting in lower energy losses and inflated efficiency readings.

At 40 percent load, the CS850M's noise remains under 40 dB(A), surpassing 45 dB(A) under 70 percent load. The fan is definitely audible under full load, though we had to push the power supply hard to make its cooler spin at full speed.

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38 comments
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  • codygriffy
    Looks very nice!
  • Shneiky
    Another CS PSU with bad caps and short life. And at 120 USD or more than 120 EUR as it appears in my district, this PSU does not stand a chance against the competition. Still a lot of people will buy it just because it has a Corsair name on it. I feel kinda bad that Corsair ruins their legacy of quality with products like CS and VS.
  • giantbucket
    550730 said:
    Another CS PSU with bad caps and short life. And at 120 USD or more than 120 EUR as it appears in my district, this PSU does not stand a chance against the competition. Still a lot of people will buy it just because it has a Corsair name on it. I feel kinda bad that Corsair ruins their legacy of quality with products like CS and VS.


    and then there are people who are going to hate on it just because it has a Corsair name on it...
  • ykki
    Nice review! Can Tom's start a psu rating system (on a scale of 1 to 10)?
  • Amdlova
    this perform really bad
  • endeavour37a
    ykki, here is a tier list of PSUs, perhaps this is what your talking about.......
    http://www.tomshardware.com/forum/id-1804779/power-supply-unit-tier-list.html
  • Sakkura
    Breaks ATX spec, high-ish 12V ripple, bad capacitors... No thanks.
  • Shneiky
    ykki,

    I do not hate Corsair products because they are Corsair. I have a Corsair K70 and I love it. What I hate is cheaply made equipment that wants a price premium because it is X brand.
  • Aris_Mp
    @ykki The relative performance graph can play this role and with much more accuracy. However it measures pure performance and doesn't take into account other factors as output noise, warranty period etc. For these factors a final rating is needed, indeed.
  • damric
    Good review, Aris.

    I see no reason to buy this PSU when there are other good units with lower price built with better components. Example: Many XFX (Seasonic) and Golden Green (Capstone/B2) cost less but are more reliable with all good caps. Unfortunately, most consumers will be suckered in by the Corsair sticker.

    On the bright side, these Great Wall units have far less problems than the CX series. Probably even more reliable than the RM.
  • endeavour37a
    The CS Series is made by Great Wall, any of their PSU made by Sea Sonic or Channel Well are good ones, so it just depends on which one you get on how the quality is.

    http://www.tomshardware.com/reviews/power-supply-psu-brands,3762-5.html
  • Sakkura
    1109232 said:
    The CS Series is made by Great Wall, any of their PSU made by Sea Sonic or Channel Well are good ones, so it just depends on which one you get on how the quality is. http://www.tomshardware.com/reviews/power-supply-psu-brands,3762-5.html


    You can't just say any Corsair units made by CWT are good. Their lowest-end series is the VS series, which is made by CWT. It's not better than these units made by Great Wall.

    Their Seasonic units are fine, but Corsair relies much less on Seasonic than it used to.
  • synphul
    I don't think it's so much that people want to hate on corsair because of their name, rather the reputation they've earned themselves. It only takes a little to earn a bad rep but takes a lot of turning that around to overcome and fix the way people regard them. Continuing to build low tier products at high prices and embracing low budget materials isn't doing them any favors.

    Companies like seasonic aren't nearly as heavily advertised and at that they're more recognized now than they used to be. Instead of cranking out tons of low quality components, they've concentrated on quality and maintained a good reputation. That's not saying every corsair is junk or seasonic never has a bad unit once in awhile. Corsair would rather flood the market with a lot of cheap units so they can't be surprised when many start avoiding the headaches and potential problems, instead investing the same money in better quality units.

    The review here is a bit confusing. On one hand it's a lower tier unit with a short(er) warranty, meant for moderate gaming. On the other it's powerful enough for 'enthusiast' builds with mulitple gpu's. Multiple gpu's are for 'moderate' gaming? If someone has an extra $300-500 for an additional gpu, surely they can muster up an additional $50 or so for a quality psu.
  • Aris_Mp
    this is a mid-level PSU, not a mainstream one, and with its true 850 W capacity can easily support at least two high-end VGAs, so it will do just fine into a gaming unit.

    Now as for the other matter you are referring, unfortunately many users while choose to invest a great amount on the mainboard, VGAs and CPU they leave the PSU for last so they buy one with the leftovers. Normally it should be the other way around since the PSU plays a key role in the health of all the rest system components.
  • endeavour37a
    551379 said:
    1109232 said:
    The CS Series is made by Great Wall, any of their PSU made by Sea Sonic or Channel Well are good ones, so it just depends on which one you get on how the quality is. http://www.tomshardware.com/reviews/power-supply-psu-brands,3762-5.html
    You can't just say any Corsair units made by CWT are good. Their lowest-end series is the VS series, which is made by CWT. It's not better than these units made by Great Wall. Their Seasonic units are fine, but Corsair relies much less on Seasonic than it used to.


    OK........
  • Shankovich
    Looks like someone read my comments on the 1600W superflower review :P.

    Looks like the OEM dropped the ball a bit. Not sure who is the CS series OEM? I think that amazing article from 2013 needs an update: http://www.tomshardware.com/reviews/power-supply-oem-manufacturer,2913-5.html
  • endeavour37a
    340939 said:
    Looks like someone read my comments on the 1600W superflower review :P. Looks like the OEM dropped the ball a bit. Not sure who is the CS series OEM? I think that amazing article from 2013 needs an update: http://www.tomshardware.com/reviews/power-supply-oem-manufacturer,2913-5.html


    Who's Who In Power Supplies, 2014: Brands Vs. Manufacturers
    http://www.tomshardware.com/reviews/power-supply-psu-brands,3762.html
  • daglesj
    Why would anyone want a 'flagship' PSU if their PC only pulls 400W at max load?
  • MasterMace
    Corsair did not build this as a gaming unit, despite being at the wattage for gaming. Having lower quality capacitors will not earn them any favors for gamers willing to drop $120 on a power supply.

    Corsair -raised- the price on their HX series. The HX 850M used to be well priced around $100-$110. I am not a fan of a company name being used to justify high prices, nor am I a fan of making worse quality products to raise the prices on old products.

    OEMs own their reputations longer than companies like Corsair who pay them to make it and slap their name on it after.
  • Shankovich
    Quote:
    340939 said:
    Looks like someone read my comments on the 1600W superflower review :P. Looks like the OEM dropped the ball a bit. Not sure who is the CS series OEM? I think that amazing article from 2013 needs an update: http://www.tomshardware.com/reviews/power-supply-oem-manufacturer,2913-5.html
    Who's Who In Power Supplies, 2014: Brands Vs. Manufacturers http://www.tomshardware.com/reviews/power-supply-psu-brands,3762.html


    Thank you hahaha, that's what I get for skipping over the links at the bottom of the page
  • ykki
    1109232 said:
    ykki, here is a tier list of PSUs, perhaps this is what your talking about....... http://www.tomshardware.com/forum/id-1804779/power-supply-unit-tier-list.html


    Who doesn't know about that lol. I am talking of a numeric based system rather than a tier based one.
  • Aris_Mp
    Take a look below. In every review there is an updated graph.

    http://www.techpowerup.com/reviews/Andyson/Titanium_N700/10.html
  • JackNaylorPE
    At least Corsair continues to provide labeling sufficient for us to determine what models to avoid. "CS - Cheap S _ _ _"
  • damric
    35894 said:
    At least Corsair continues to provide labeling sufficient for us to determine what models to avoid. "CS - Cheap S _ _ _"


    X stands for DO NOT BUY.

    RM stands for RMA soon.