Corsair CX650M PSU Review

Transient Response Tests

Advanced Transient Response Tests

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

Ιn these tests, we monitor the CX650M's response in two different scenarios. First, a transient load (10 A at +12V, 5 A at 5V, 5 A at 3.3V, and 0.5 A at 5VSB) is applied for 200ms while the PSU works at 20 percent load. In the second scenario, the CX650M is hit by the same transient load while operating at 50 percent load. In both tests we use 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
12V12.094V11.938V1.29%Pass
5V5.021V4.966V1.10%Pass
3.3V3.287V3.185V3.10%Pass
5VSB5.066V5.030V0.71%Pass

Advanced Transient Response at 50 Percent

VoltageBeforeAfterChangePass/Fail
12V12.048V11.893V1.29%Pass
5V5.007V4.952V1.10%Pass
3.3V3.276V3.157V3.63%Pass
5VSB5.030V5.001V0.58%Pass

It would be nice if the +12V deviations stayed within 1%, but we can't be that picky with such an affordable PSU. The 5V and 5VSB rails have low deviations, while 3.3V registers the worst performance. In both tests the 3.3V rail drops its voltage below 3.2 V as soon as the transient load is applied.

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

Transient Response At 20 Percent Load

Transient Response At 50 Percent Load

Turn-On Transient Tests

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

For the first measurement, we turn off the PSU, dial in the maximum current the 5VSB can output, and switch it back on. In the second test, we dial the maximum load the +12V rail can handle and start the PSU while it's in standby mode. In the last test, while the CX650M is completely switched off, we dial the maximum load the +12V rail can handle before switching the PSU 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 13.2 V, and 5.5 V for 5V).    

The 5VSB slope is perfect. The +12V slopes are pretty good as well, with the last one featuring a very brief period of increased ripple. That's nothing to worry about, though.

This thread is closed for comments
44 comments
    Your comment
  • Dark Lord of Tech
    Thanks for the review on this new CXM platform.
  • JQB45
    Looks to be better then the old CX line up.
  • Onus
    Good to see that Corsair didn't produce a[nother] Turkey with this one.
  • turkey3_scratch
    Onus why would Corsair produce me?

    Anyway I think the price/performance page shows all. This thing rocks!

    Also Jonnyguru claims it is a rifle bearing fan that has the same model # as the sleeve variant.
  • benedict78
    Does the CX650 perform the same as the CX650M? I'm not interested in modularity anyway.
  • turkey3_scratch
    The CX650 is not out yet.
  • Aris_Mp
    I have several CM and CX-M units, which I plan to fully evaluate. So far I figured that there are differences (something natural of course) in their performance.
  • Dark Lord of Tech
    Could you put the newer CXM 750W OR 850W on deck soon , as they are widely use for DUAL CARD configurations.
  • turkey3_scratch
    The 750W and 850W CXM units are basically unchanged except for a bridge rectifier upgrade. Everything else is the same. Only the CX450-650M got the major revisions.
  • Dark Lord of Tech
    Yeah I know that , but want to see one reviewed , to compare top older generations.
  • Ryan_78
    Seems cool to be a CX now. Nice
  • bettsar
    After getting such high marks from the review, why no award?
  • Aris_Mp
    The CX750M is on the test bench right now. I don't have a CX850M sample.
  • Aris_Mp
    About the award. It should have a recommendation award but as it seems we forgot to add it. On it right now :)
  • Math Geek
    good to see them making a strong performer in a moderate price range. if they drop some massive rebates over the holidays like they do most years, this will be a super buy. i'm keeping my eye out to stock up on some. looks like a very solid buy.
  • atljsf
    the modularity is nice if you have a mini itx case, i have a cx500 and some of the unused cables are a bit inconvenient so that cx650m should be nice for those with not that small mini itx cases that can fit normal size psus
  • HERETIC-1
    Corsair spend $3 more and get all Jap capacitors and you'll have a good PSU.
    Oh you have-It's called the Vengeance series.(RECOMMENDED)
  • turkey3_scratch
    HERETIC you are severely misled. Do you realize there are Chinese capacitors of higher quality than Japanese? Do you realize how much ripple a capacitors handles and the environment the capacitors is in also affects it's lifespan a lot?

    Look at the thermal shots. The PSU is significantly cooler than was expected. That is fantastic for capacitor life. If you want to persist at judging power supplies based on capacitors country (and BTW a lot of Jap caps are outsourced to China) then you will be misled.
  • HERETIC-1
    So turkey are you saying Corsair's marketing "105C JAPANESE CAPACITORS"
    on their vengeance series is not necessary?
    I am more than happy to pay a little more when I see-
    "All electrolytic caps come from Nippon Chemi-Con"
  • turkey3_scratch
    The Vengeance series is a higher end unit than the CXM at a different price category for different countries. Not really fair to compare them.

    What more.could you possibly want at the price this thing sells for? This is the best value period and you have to find the need to talk about Japanese caps without even knowing the spec sheets of these caps used.
  • 10tacle
    "Finally, the number of provided cables and connectors is sufficient for this unit's capacity. And although it isn't fully modular, the native cables are absolutely necessary anyway."

    I've never understood the logic behind a "fully" modular PSU where all cables are completely disconnected and need to be plugged in. How exactly are you not going to use a PSU in a PC without the 20+4 pin ATX and 8 pin 12v CPU power connectors going to the motherboard?

    If anything, I'd want those connected directly during manufacturing to ensure nothing is lost (output or resistance) through a transfer connector port to the two most crucial power connectors.
  • atljsf
    202972 said:
    "Finally, the number of provided cables and connectors is sufficient for this unit's capacity. And although it isn't fully modular, the native cables are absolutely necessary anyway." I've never understood the logic behind a "fully" modular PSU where all cables are completely disconnected and need to be plugged in. How exactly are you not going to use a PSU in a PC without the 20+4 pin ATX and 8 pin 12v CPU power connectors going to the motherboard? If anything, I'd want those connected directly during manufacturing to ensure nothing is lost (output or resistance) through a transfer connector port to the two most crucial power connectors.


    the idea is that if you want a longer, half meter or a shorter, 15 centimeters long cable, you can change the one that came with the psu and put the one you need

    this is what most pc builders need this days, especially with mini itx cases where space is extremely limited
  • JQB45
    2011305 said:
    the idea is that if you want a longer, half meter or a shorter, 15 centimeters long cable, you can change the one that came with the psu and put the one you need this is what most pc builders need this days, especially with mini itx cases where space is extremely limited


    So If I buy power supply "A" for my mITX build and its fully modular but the cables are to long, where do I go to get shorter cables?
  • turkey3_scratch
    Cables cost like $100.