Corsair RM750 Power Supply Review: Affordable Yet Powerful

Load Regulation, Hold-Up Time, Inrush Current, Efficiency and Noise

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

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Primary Rails And 5VSB Load Regulation

The following charts show the main rails' voltage values recorded between a range of 40W up to the PSU's maximum specified load, along with the deviation (in percent). Tight regulation is an important consideration every time we review a power supply, because it facilitates constant voltage levels despite varying loads. Tight load regulation also, among other factors, improves the system’s stability, especially under overclocked conditions and, at the same time, it applies less stress to the DC-DC converters that many system components utilize.



The load regulation is satisfactory at +12V and tight on the minor rails. 

Hold-Up Time

Put simply, hold-up time is the amount of time that the system can continue to run without shutting down or rebooting during a power interruption.

The hold-up time exceeds 17ms, while the power ok signal is accurate. 

Inrush Current

Inrush current, or switch-on surge, refers to the maximum, instantaneous input current drawn by an electrical device when it is first turned on. A large enough inrush current can cause circuit breakers and fuses to trip. It can also damage switches, relays, and bridge rectifiers. As a result, the lower the inrush current of a PSU right as it is turned on, the better.

The inrush current is at normal levels with 115V input. With 230V is on the high side, though. 

10-110% Load Tests

These tests reveal the RM750’s load regulation and efficiency levels under high ambient temperatures. They also show how the fan speed profile behaves under increased operating temperatures.

Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)PSU Noise (dB[A])Temps (In/Out)PF/AC Volts
14.360A1.985A2.005A0.997A74.49386.177%0<6.042.73°C0.974
12.130V5.040V3.291V5.018V86.44239.84°C115.12V
29.778A2.979A3.010A1.197A149.39289.931%0<6.044.42°C0.988
12.118V5.037V3.288V5.013V166.11940.76°C115.11V
315.625A3.477A3.500A1.398A224.89891.626%0<6.045.61°C0.991
12.089V5.035V3.286V5.007V245.45141.07°C115.11V
421.399A3.975A4.021A1.600A299.66591.584%0<6.046.67°C0.993
12.078V5.033V3.283V5.000V327.20241.78°C115.11V
526.864A4.972A5.029A1.802A374.61391.076%78015.942.36°C0.992
12.064V5.031V3.283V4.995V411.31847.71°C115.11V
632.324A5.969A6.038A2.005A449.55090.439%78116.042.84°C0.992
12.057V5.028V3.280V4.989V497.07649.23°C115.11V
737.842A6.965A7.045A2.208A524.84289.803%78316.144.18°C0.993
12.043V5.026V3.279V4.984V584.44051.16°C115.12V
843.338A7.967A8.058A2.412A600.16988.985%112228.144.50°C0.994
12.039V5.022V3.277V4.978V674.45852.21°C115.12V
949.212A8.468A8.546A2.412A674.68488.241%140734.845.39°C0.995
12.033V5.021V3.276V4.976V764.59053.79°C115.12V
1054.905A8.970A9.071A3.026A749.95487.314%163339.046.43°C0.995
12.025V5.018V3.275V4.958V858.91455.76°C115.12V
1161.186A8.974A9.075A3.028A825.17686.487%175340.846.81°C0.995
12.020V5.016V3.273V4.955V954.10057.49°C115.12V
CL10.139A18.005A18.001A0.000A151.02282.858%1007 24.642.50°C0.989
12.116V5.015V3.280V5.070V182.26747.74°C115.14V
CL262.520A1.004A1.001A1.000A765.55987.755%1715 40.446.14°C0.995
12.032V5.026V3.272V4.997V872.38755.29°C115.12V

The passive operation lasts for quite long if the load on the minor rails remains low. With 20%, 50% and full load the power supply easily meets the corresponding 80 PLUS Gold standard's requirements, even under the high operating temperatures that we apply. 

20-80W Load Tests

In the following tests, we measure the RM750's efficiency at loads significantly lower than 10% of its maximum capacity (the lowest load the 80 PLUS standard measures). This is important for representing when a PC is idle with power-saving features turned on.

Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)PSU Noise (dB[A])PF/AC Volts
11.193A0.496A0.483A0.199A19.51080.103%0<6.00.829
12.088V5.038V3.289V5.034V24.356115.11V
22.452A0.992A1.002A0.398A39.96085.039%0<6.00.936
12.096V5.039V3.292V5.031V46.990115.11V
33.642A1.488A1.488A0.597A59.44786.615%0<6.00.963
12.095V5.039V3.292V5.027V68.634115.11V
44.885A1.984A2.005A0.796A79.84186.791%0<6.00.975
12.128V5.039V3.292V5.023V91.992115.11V

High efficiency numbers and minimized noise output, since the PSU's fan is not spinning.

Efficiency

Next, we plotted a chart showing the RM750’s efficiency at low loads, and loads from 10 to 110% of its maximum-rated capacity. The higher a PSU’s efficiency, the less energy goes wasted leading to a reduced carbon footprint, besides lower electricity bills.

The efficiency under light loads is super high.

5VSB Efficiency

Test #5VSBDC/AC (Watts)EfficiencyPF/AC Volts
10.100A0.50776.012%0.066
5.063V0.667115.10V
20.250A1.26577.798%0.149
5.059V1.626115.10V
30.550A2.77878.563%0.260
5.051V3.536115.10V
41.000A5.03977.583%0.348
5.039V6.495115.10V
51.500A7.53977.426%0.396
5.026V9.737115.11V
63.000A14.95876.653%0.457
4.986V19.514115.11V

The 5VSB rail is efficient enough. 

Power Consumption In Idle And Standby

Mode12V5V3.3V5VSBWattsPF/AC Volts
Idle12.078V5.035V3.292V5.034V3.0510.240
115.1V
Standby0.0360.004
115.1V

Fan RPM, Delta Temperature, And Output Noise

All results are obtained between an ambient temperature of 37 to 47 degrees Celsius (98.6 to 116.6 degrees Fahrenheit).


With light loads on the minor rails, the unit's passive operation lasts up to 300W loads, even under high operating temperatures. 

The following results were obtained at 30 to 32 degrees Celsius (86 to 89.6 degrees Fahrenheit) ambient temperature.       

Because we push hard the minor rails (5V & 3.3V), the power supply engages its passive operation only for very short periods. Nonetheless, the fan speed is kept low in general and so does the output noise.

MORE: Best Power Supplies

MORE: How We Test Power Supplies

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1 comment
    Your comment
  • DSzymborski
    It's really hard to recommend this at the price. Offer this at $75 and it's interesting, but there's always something better at this price that'll undercut it and a few additional sales that put under this (SeaSonic Focus, EVGA G3, etc). I don't think this is even competitive at $100.