Corsair RM650x 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 PSU'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) is applied for 200 ms while the PSU works at 20 percent load. In the second scenario, the PSU 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
12V12.045V11.979V0.55%Pass
5V5.038V4.980V1.15%Pass
3.3V3.312V3.243V2.08%Pass
5VSB5.014V4.979V0.70%Pass

Advanced Transient Response at 50 Percent

VoltageBeforeAfterChangePass/Fail
12V12.001V11.938V0.52%Pass
5V5.029V4.974V1.09%Pass
3.3V3.308V3.240V2.06%Pass
5VSB4.996V4.953V0.86%Pass

The +12V rail performs amazingly in these tests. Even the 3.3V rail, which usually exceeds 3% deviation, stayed close to 2% in this case. Corsair's platform is great here, and with slightly tighter +12V load regulation it could give the competition serious headaches (not that it hasn't already).

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 measured the response of the PSU in simpler transient load scenarios—during the PSU's power-on phase.

For the first measurement, we turned off the PSU, dialed in the maximum current the 5VSB could output and switched on the PSU. In the second test, we dialed the maximum load the +12V could handle and started the PSU while it was in standby mode. In the last test, while the PSU was completely switched off (we cut the power or switched the PSU off by flipping its on/off switch), we dialed the maximum load the +12V rail could 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 13.2V, and 5.5V for 5V).    

There are no spikes or voltage overshoots here. With a slightly smoother slope in the last test, the result would be perfect. 

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27 comments
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  • maxwellmelon
    for all the good listed in this article, this series of psu just gets bashed in the fourms, just interesting.
  • basroil
    1432275 said:
    for all the good listed in this article, this series of psu just gets bashed in the fourms, just interesting.


    You're thinking of the older RM650, different design.

    The review here just made this unit be one of my recommended 650 models, tied with the EVGA G2/P2 and just below the Seasonic 660XP2!
  • pjc6281
    I have had this PSU for my new Skylake build for 2 months. Its GREAT, quiet and even have it pushing my old dinosaur Nvidia 590 with no problems. My old power supply was a Corsair AX1200 that was rock solid as well. Nothing but good experiences with them. I know others differ.
  • Dark Lord of Tech
    RMX doesn't get bashed , RMX and RMI are very very good. I own the RMX 850 , GREAT UNIT.
  • TechyInAZ
    I'm glad the new RM series is much higher quality. All I remember Corsair having is a bunch of bad PSUs with select few good PSU (like AX and HX).

    I hope this same kind of quality intros into other models like the newly refreshed CX PSUs.
  • anort3
    1432275 said:
    for all the good listed in this article, this series of psu just gets bashed in the fourms, just interesting.


    Yeah, I believe you are confusing the RMx and RMi with the older, mostly discontinued RM line. And of the old RM line only the 750w and 850w versions that were first made by Chicony Power Technology had the bad reputation. Anyone bashing the RMx and RMi doesn't know what they are talking about. Once misinformation gets out there it's hard to get it corrected though.

    Another great review Aris! :)
  • Nintendork
    Why buy Corsair or EVGA when you can get a Seasonic?
  • anort3
    205977 said:
    Why buy Corsair or EVGA when you can get a Seasonic?


    Seasonic doesn't have a lock on quality. They also don't offer a 10 year warranty which both Corsair and EVGA do on some models. Just off the top of my head Flextronics, CWT and SuperFlower are all capable of making units that are at least equal to high end Seasonic quality. There are others as well.
  • TechyInAZ
    218893 said:
    205977 said:
    Why buy Corsair or EVGA when you can get a Seasonic?
    Seasonic doesn't have a lock on quality. They also don't offer a 10 year warranty which both Corsair and EVGA do on some models. Just off the top of my head Flextronics, CWT and SuperFlower are all capable of making units that are at least equal to high end Seasonic quality. There are others as well.


    Plus, efficiency levels are typically better with EVGA than Seasonic.
  • anort3
    1695593 said:
    218893 said:
    205977 said:
    Why buy Corsair or EVGA when you can get a Seasonic?
    Seasonic doesn't have a lock on quality. They also don't offer a 10 year warranty which both Corsair and EVGA do on some models. Just off the top of my head Flextronics, CWT and SuperFlower are all capable of making units that are at least equal to high end Seasonic quality. There are others as well.
    Plus, efficiency levels are typically better with EVGA than Seasonic.


    :??: Not sure what you mean. EVGA has a couple of 80 Plus Titanium models but Seasonic has Titanium models in their new lineup. I'm not sure if those new Seasonic models are available yet though. Other than that I've had an 80 Plus Platinum Seasonic ( 660XP2 ) for a couple of years and their Platinum line has been out since at least 2011.
  • TechyInAZ
    Sorry I should of clarified. I mean the SuperNOVA G2 vs the gold 550W Seasonic PSUs.
  • Dark Lord of Tech
    The last few I have purchased are RMX , love them.
  • turkey3_scratch
    205977 said:
    Why buy Corsair or EVGA when you can get a Seasonic?


    Seasonic is not perfect. Many users are actually experiencing issues with Seasonic's Platinum lineup of units http://www.jonnyguru.com/forums/showthread.php?t=11038
  • Dark Lord of Tech
    All manufactures have issues two more PM's today , one about a DOA EVGA 600B and , 1 about a DOA Seasonic S12 , it happens , I told them , even the great ones have a few mixed in.
  • turkey3_scratch
    276663 said:
    All manufactures have issues two more PM's today , one about a DOA EVGA 600B and , 1 about a DOA Seasonic S12 , it happens , I told them , even the great ones have a few mixed in.


    But in this case there is a lot of people experiencing similar problems on Seasonic Platinum based units. Not that random DOA unit.
  • Dark Lord of Tech
    I was talking problems in General , all units have some any brand can have a few hiccups.


    That never brings a solid brand down.

  • turkey3_scratch
    That's what I love about these RMx units, it's near impossible to find a hiccup.
  • Dark Lord of Tech
    I love them , very impressed by the SF series too.
  • powernod
    Aris keeps making his reviews wider & even more detailed! His new addition , "evaluating protection features", is another crucial addition at the PSU Review field!! If he continoues this way, soon , every review of him, will be a standalone book!!:wahoo:
  • dark-ice
    I wanted to buy an EVGA P2 650W but amazon doesn't have stock, so I think I'm going to buy this one instead.
  • Dark Lord of Tech
    I'll stick to GURU.
  • turkey3_scratch
    Blackbird, I think by restricting yourself to Jonny guru is not too smart, there is so much more information available from these reviews. It is always good to look at multiple review sites, not one.
  • Kimonajane
    I have corsair in my current rig, no problems at all for years. No crashes due to power fluctuation like you can get from cheap PSU.
  • captaincharisma
    1432275 said:
    for all the good listed in this article, this series of psu just gets bashed in the fourms, just interesting.


    the only Corsair PSU's i see getting bashed in the forums are their CX line of PSU's. mind you people are bashing them yet they don't realize the CX line is not meant for anything other then office computers

    I've been running a Corsair HX750 for almost 4 years now and has never skipped a beat