Corsair CS850M 850W Power Supply Review

Efficiency, Temperatures And Noise

Efficiency

Using the previous page's results, we plotted a chart showing efficiency at low loads and at loads equal to 10 percent to 110 percent of the PSU's maximum rated capacity.

Under normal loads, the unit's efficiency lands it in the middle of its market segment. At light loads, the CS850M scores a second-place finish behind the high-end Cooler Master V850, which utilizes a cutting-edge platform that costs significantly more. In general, Corsair's offering performs well in our efficiency tests. That should make prospective customers happy, since they'll save money on power over time.

Efficiency at Low Loads

In the next tests, we measure the efficiency of the CS850M at loads significantly lower than 10 percent of the device's maximum capacity (the lowest load the 80 PLUS standard measures). The loads we dialed were 20, 40, 60 and 80W. This is important for representing when a PC is idle with power-saving features turned on.

Test #12V
5V
3.3V5 VSB
Power
DC/AC (W)
Efficiency (%)
Fan Speed (RPM)
Fan Noise (dB[A])
PF/AC (V)
11.198A0.490A0.477A0.195A19.6665.58757
30.9
0.775
12.176V5.075V3.347V5.066V29.98115.1
22.421A0.978A0.985A0.394A39.7176.26757
30.9
0.915
12.170V5.072V3.344V5.056V52.07115.1
33.648A1.472A1.495A0.590A59.8382.04790
31.7
0.953
12.170V5.066V3.343V5.045V72.93115.1
44.862A1.972A1.974A0.790A79.7484.68828
33.5
0.962
12.172V5.063V3.341V5.036V94.17115.1

Efficiency is pretty good at low loads. As you can see in the above table, even under a mere 20W load, the CS850M stays above 65 percent. Also, the fan spins at low speeds during these tests, despite the greater-than 35 °C temperature inside our hot box. 

5VSB Efficiency

The ATX specification states that 5VSB standby supply efficiency should be as high as possible, recommending 50 percent or higher efficiency with 100mA of load, 60 percent or higher with 250mA of load and 70 percent or higher with 1A or more of load.

We will take four measurements at 100, 250 and 1000mA, and one under the highest load the 5VSB rail can handle. 

Test #5VSB
Power DC/AC (W)
Efficiency (%)
PF/AC (V)
10.102A0.5278.790.049
5.072V0.66115.3
20.252A1.2881.530.111
5.066V1.57115.3
31.002A5.0482.760.272
5.033V6.09115.3
43.002A14.8478.190.436
4.945V18.98115.2

The 5VSB rail's efficiency is among the best we have seen in the tests with 0.25 and 1A loads. The only thing spoiling the overall picture is a significant efficiency drop during the full load test, which indicates that 3A on this rail pushes the 5VSB regulation circuit hard.

Power Consumption in Idle And Standby

Mode12V5V3.3V5VSBPower (AC)PF/AC Volts
Idle12.466V5.078V3.351V5.076V13.20W0.492
115.3V
Standby 0.08W0.004
115.3V

In the table above, you'll find the power consumption and voltage values of all rails (except -12V) when the PSU is idle (powered on, but without any load on its rails), along with the power consumption when the PSU is in standby mode (without any load at 5VSB).

With 115VAC input, the PSU’s energy demands are very low. They increase with 230VAC, though the CS850M still meets the strict ErP Lot 6 2013 requirements.

Fan RPM, Delta Temperature And Output Noise

The above chart illustrates the cooling fan's speed (in RPM), along with the delta between input and output temperature. The results were obtained at 35 to 48 °C ambient temperature.   

This chart shows the cooling fan's speed (in RPM) and output noise. We measured acoustics from one meter away, inside a small, custom-made anechoic chamber with internals completely covered in soundproofing material (be quiet! Noise Absorber kit). Background noise inside the anechoic chamber was below 18 dB(A) during testing, and the results were obtained with the PSU operating at 35 to 48 °C ambient temperature. 

The following graph illustrates the fan's output noise over the PSU's entire operating range. The same conditions of the above graph apply to our measurements, though the ambient temperature was between 28 and 30 °C.  

At up to around 450W, the CS850M is pretty quiet; it starts to make its presence known with more than 550W of load. In general, this PSU isn't obtrusive, though it doesn't benefit from a semi-passive mode under light loads.

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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.