Corsair CX650M PSU Review

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Load Regulation, Hold-Up Time, And Inrush Current

To learn more about our PSU tests and methodology, please check out How We Test Power Supply Units. 

Primary Rails And 5VSB Load Regulation

Load Regulation testing is detailed here.

Hold-Up Time

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

The hold-up time we measured hits the spot, while the power-good signal lasts for shorter than required. At least it drops before the rails go out of spec, providing accurate information to the motherboard. This is a huge deal since we've seen a number of PSUs (including some high-end ones) have problems providing accurate power-good information. 

Inrush Current

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

The inrush current with 115V is quite high, while with 230V it's normal for 650W unit.

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 to 110 percent of the maximum load the supply can handle, in increments of 10 percentage points.

We conducted two additional tests. During the first, we stressed the two minor rails (5V and 3.3V) with a high load, while the load at +12V was only 0.1 A. This test reveals whether a PSU is Haswell-ready or not. In the second test, we determined the maximum load the +12V rail could handle with minimal load on the minor rails. 

Swipe to scroll horizontally
Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan SpeedFan NoiseTemps (In/Out)PF/AC Volts
13.566A1.984A2.003A0.980A64.7381.46%840 RPM27.7 dB(A)36.49°C0.972
28.174A2.981A3.009A1.180A129.6987.07%840 RPM27.7 dB(A)37.38°C0.988
313.145A3.488A3.530A1.383A194.8588.22%840 RPM27.7 dB(A)38.54°C0.994
418.118A3.988A4.021A1.585A259.7388.43%840 RPM27.7 dB(A)39.47°C0.996
522.765A4.986A5.034A1.785A324.7088.16%840 RPM27.7 dB(A)41.90°C0.997
627.419A5.994A6.050A1.990A389.7087.26%1200 RPM36.1 dB(A)42.17°C0.996
732.083A7.007A7.069A2.195A454.6586.41%1430 RPM37.0 dB(A)43.12°C0.997
836.768A8.010A8.091A2.404A519.6485.43%1685 RPM39.5 dB(A)43.70°C0.997
941.889A8.516A8.624A2.405A584.5984.47%1950 RPM42.2 dB(A)44.31°C0.997
1046.773A9.033A9.127A3.020A649.5383.30%2240 RPM45.5 dB(A)45.03°C0.998
1152.278A9.040A9.134A3.025A714.5882.50%2240 RPM45.5 dB(A)45.22°C0.998
CL10.100A16.024A16.004A0.003A133.5081.94%840 RPM27.7 dB(A)41.64°C0.990
CL253.963A1.002A1.003A1.001A659.2483.98%2240 RPM45.5 dB(A)44.28°C0.998

For such an affordable PSU, load regulation is pretty tight! All major rails are within 1.5%, with only 5VSB exceeding 2%. The CX650M surprises us in a good way by performing much better than we were expecting. When it comes to efficiency, the CX650M easily meets the fairly loose 80 PLUS Bronze requirements, although under higher loads efficiency takes a large hit. The synchronous design on the secondary side and the DC-DC converters that generate the minor rails surely play a large role in this.

Besides good performance, the CX650M also manages to offer quiet operation (even under high operating temperatures), so long as the applied load doesn't exceed 50% of its max-rated capacity. The only downside is that Corsair's minimum fan speed is quite high at 840 RPM. It could easily be lower than 600 RPM. In any case, output noise only exceeds 40 dB(A) with 90% and higher loads.

Contributing Editor

Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.

  • 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 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.