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Corsair CX750M PSU Review

Corsair's CX line is aimed at users with limited budgets who still want a branded, reliable, and well-supported PSU. Today we're reviewing the second-strongest member of the family, the CX750M.

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Transient Response Tests

Advanced Transient Response Tests

For details on our transient response testing, please click here.

Ιn these tests, we monitored the CX750M's response in two different scenarios. First, a transient load (10A at +12V, 5A at 5V, 5A at 3.3V, and 0.5A at 5VSB) was applied for 200ms while the PSU worked at 20 percent load. In the second scenario, Corsair's contender was hit by the same transient load while operating at 50 percent load. In both tests, we used our oscilloscope to measure the voltage drops caused by the transient load. The voltages should remain within the ATX specification's regulation limits.

These tests are crucial because they simulate the transient loads a PSU is likely to handle (such as booting a RAID array or an instant 100 percent load of CPU/GPUs). We call these tests "Advanced Transient Response Tests," and they are designed to be very tough to master, especially for a PSU with a capacity of less than 500W.

Advanced Transient Response at 20 Percent

VoltageBeforeAfterChangePass/Fail
12V12.042V11.883V1.32%Pass
5V5.024V4.905V2.37%Pass
3.3V3.295V3.146V4.52%Pass
5VSB5.012V4.896V2.31%Pass

Advanced Transient Response at 50 Percent

VoltageBeforeAfterChangePass/Fail
12V11.977V11.822V1.29%Pass
5V4.992V4.868V2.48%Pass
3.3V3.273V3.116V4.80%Fail
5VSB4.957V4.815V2.86%Pass
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The +12V rail's transient response isn't so good. We also notice large deviations on the 5VSB rail. The 5V rail performs well, but this isn't the case for the 3.3V rail, which fails to keep its load regulation within spec during the second test.

Here are the oscilloscope screenshots we took during Advanced Transient Response Testing:

Transient Response At 20 Percent Load

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Transient Response At 50 Percent Load

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Turn-On Transient Tests

In the next set of tests, we measured the response of the PSU in simpler transient load scenarios—during its power-on phase.

For the first measurement, we turned off the CX750M, dialed in the maximum current its 5VSB rail could output, and switched the PSU back on. In the second test, we dialed the maximum load the +12V rail could handle and started the 750W supply while it was in standby mode. In the last test, while the PSU was completely switched off, we dialed the maximum load the +12V rail could handle before switching it back on from the loader and restoring power. The ATX specification states that recorded spikes on all rails should not exceed 10 percent of their nominal values (+10 percent for 12V is 13.2V, and 5.5V for 5V).

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There is a tiny spike at 5VSB, while the slope in the second test is very smooth. Things aren't as great in the third test, but we've seen pricier PSUs fare worse in this test, too.

Aris Mpitziopoulos
Aris Mpitziopoulos
Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.
26 Comments Comment from the forums
  • Bit early for a review,but just installed mine to replace my old one that was power surging.
    Very easy to install and only use the extra cables you need.
    Piece of mind knowing the 3 year warranty that comes with it.
    Reply
  • RCFProd
    Thanks for the review!
    Reply
  • turkey3_scratch
    Funny how it doesn't have OTP, when as a matter of fact, OTP was the very thing that saved the original CX750M's butt in Jonnyguru's testing; but the majority of people, rather than realizing that was a good safety measure, took it instead as "the CX750M can't do more than 650W" when in fact it was just Oklahomawolf's hot box. So maybe to avoid another mishap like this altogether they just removed OTP and cheered over the money savings at the same time?

    I don't care for this PSU too much anyway. It seems to be a power supply that likes to focus on good ripple (as every modern PSU does these days) and decent voltage regulation but falls short in nearly every other aspect. I don't see it being much of any improvement over the original CX750M, the whole purpose of was probably just to cut costs. I'd happily take 60mv of ripple on my 12V rail in turn for some better holdup time, a higher quality fan and perhaps caps (if those Suscons aren't the best), and OTP.
    Reply
  • jonnyguru
    It does have OTP. There's something wrong with Aris's unit and I'm going to investigate it.
    Reply
  • JackNaylorPE
    I keep reading posts referencing the new CXM series, but the conclusions section which most readers skip to seem to follow Mom's advice ... "if ya don't have anything good to say, don't say anything" ... anything negative is left out. If the CX750M is going to be competitive, it has to address the elephant in the room that is the EVGA 750 B2 that sells for $50.
    Reply
  • RCFProd
    18929743 said:
    I keep reading posts referencing the new CXM series

    Aren't those usually either the 450w, 550w and 650 watts? Those are different units compared to the 750 watts I think.

    18929743 said:
    If the CX750M is going to be competitive, it has to address the elephant in the room that is the EVGA 750 B2 that sells for $50.

    Plenty of better options for power supplies around CX750M's price range, must be said. Isn't the EVGA B2 750w 65 dollars?
    Reply
  • turkey3_scratch
    Ya B2 is well priced http://www.newegg.com/Product/Product.aspx?Item=N82E16817438028&cm_re=evga_750_b2%5c-_-17-438-028-_-Product
    Reply
  • JackNaylorPE
    The CX450M, CX550M and CX650M were redesigned last year and manufactured by CWT using a custom Corsair design, while the CX750M (and I think the 850 model) was based upon CWTs PUQ B patform. This latest revision seems to be even newer .. and even beyond that, it appears to have changed yet again after the review samples went out as noted in the article the newer 650M's use a "470uF bulk cap but use instead a 330uF one".

    Note that the CXM series is reported as the lowest quality Corsair PSU available in the US.... yet several VS models remain available thru US e-tailers. One thing I have always observed, specifically with regard to PSUs and coolers is that forum posters, even when referencing an article that says the reviewed item was a "good budget model" or "good for the money, tend to drop the words "budget" and "for the money" when recommending it. So while it may be a logical choice for a G3258 or GTX 1050 build w/ no overclocking, I don't quite understand why a Hyper 212 or a CX series PSU gets recommended for a 6700k / 1070 build especially where OP states an interest in overclocking the bejeezes out of everything.

    Here's the only reviews I have seen besides this one:
    http://www.tomshardware.com/reviews/corsair-cx650m-psu,4770.html
    http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=486


    18929767 said:

    Aren't those usually either the 450w, 550w and 650 watts? Those are different units compared to the 750 watts I think.

    Plenty of better options for power supplies around CX750M's price range, must be said. Isn't the EVGA B2 750w 65 dollars?

    NCIX almost always has it for $50 in conjunction w/ Corsair MIR and instant savings... sometimes others like newegg

    NCIX = $45 (Savings Code 97531-1714. SAVE $25.00 off our regular price of $89.99 Special price ends 11/30/2016 + Save $20.00 USD with manufacturer's mail-in rebate!)
    http://www.ncixus.com/products/?usaffiliateid=1000031504&sku=97531&promoid=1714

    newegg = $89.99 - $20 instant savings - $20.00 rebate card = $49.99
    http://www.newegg.com/Product/Product.aspx?Item=N82E16817438028
    Reply
  • powernod
    If i was short on budget i wouldn't hesitate to use Corsair's CX-M line of PSUs.
    Solid units for that kind of price.
    I don't expect to have Seasonic PRIME 750's performance with 80$ !!
    Reply
  • turkey3_scratch
    18930459 said:
    If i was short on budget i wouldn't hesitate to use Corsair's CX-M line of PSUs.
    Solid units for that kind of price.
    I don't expect to have Seasonic PRIME 750's performance with 80$ !!

    If I needed 750W and it was between the EVGA 750 B2 and the CX750M, I'd probably take the former.
    Reply