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Corsair RM750i Power Supply Review

Corsair is revamping its RM line, adding the letter "i" to highlight a more advanced digital interface — today we check out the RM750i.

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.

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Hold-Up Time

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

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The hold-up time was pretty long, which we expected from the increased combined capacity of the bulk caps.

Inrush Current

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

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The inrush current is at normal levels for a 750 W PSU equipped with two large bulk caps.

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 0.10A. 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. 

Test12V5V3.3V5VSBPower(DC/AC)EfficiencyFan SpeedFan NoiseTemp(In/Out)PF/AC Volts
10% Load4.392A2.002A1.980A1.002A74.76W84.63%0 RPM0 dB(A)47.44 °C0.968
12.106V4.999V3.331V4.975V88.34W41.43 °C115.1V
20% Load9.833A3.000A2.972A1.205A149.76W88.86%0 RPM0 dB(A)48.34 °C0.989
12.090V4.998V3.329V4.972V168.53W41.84 °C115.1V
30% Load15.635A3.507A3.485A1.405A224.88W90.10%0 RPM0 dB(A)49.87 °C0.993
12.075V4.994V3.326V4.968V249.59W42.62 °C115.1V
40% Load21.438A4.004A3.967A1.610A299.72W90.40%0 RPM0 dB(A)51.39 °C0.995
12.060V4.994V3.324V4.963V331.55W43.45 °C115.1V
50% Load26.919A4.999A4.963A1.810A374.67W90.23%0 RPM0 dB(A)53.71 °C0.996
12.045V4.993V3.323V4.960V415.24W44.37 °C115.1V
60% Load32.413A6.013A5.958A2.015A449.64W89.77%488 RPM22.4 dB(A)41.97 °C0.997
12.028V4.990V3.321V4.955V500.86W49.09 °C115.1V
70% Load37.919A7.014A6.959A2.220A524.59W89.21%608 RPM25.3 dB(A)43.34 °C0.997
12.013V4.988V3.319V4.950V588.07W50.70 °C115.1V
80% Load43.446A8.022A7.957A2.423A599.56W88.63%744 RPM29.7 dB(A)44.85 °C0.997
11.996V4.986V3.318V4.946V676.48W52.50 °C115.1V
90% Load49.424A8.522A8.474A2.424A674.61W87.90%848 RPM32.6 dB(A)45.17 °C0.997
11.979V4.984V3.316V4.946V767.49W53.15 °C115.1V
100% Load55.153A9.035A8.959A3.040A749.45W87.06%944 RPM34.4 dB(A)46.42 °C0.997
11.962V4.983V3.315V4.932V860.84W54.93 °C115.1V
110% Load61.504A9.039A8.963A3.040A824.37W86.23%1200 RPM41.0 dB(A)47.48 °C0.997
11.945V4.981V3.313V4.930V956.04W56.26 °C115.1V
Cross-Load 10.098A18.022A18.003A0.004A150.94W81.48%688 RPM26.9 dB(A)46.23 °C0.991
12.077V4.992V3.320V5.050V185.25W53.48 °C115.1V
Cross-Load 262.448A1.002A1.003A1.002A760.38W87.50%960 RPM34.6 dB(A)48.46 °C0.997
11.963V4.991V3.324V4.970V869.02W56.95 °C115.1V

Load regulation on the +12V rail was good, although we would like to see a reading within 1 percent. On the rest of the rails regulation was much tighter, with the 5V and 3.3V rails easily staying well below 1 percent. In addition, efficiency easily met the 80 Plus Gold requirements with 20 percent and 50 percent load; however, with a full load it was very close to the lower allowed level. As a reminder, the 80 Plus organization conducts the certification tests at only 23 C (73.4 F), while we test at a much higher ambient temperature, so it is natural to measure significantly lower efficiency throughout all load ranges.

In the noise output section, the RM750i carries on the tradition of the RM line with its silent operation, even under extremely tough conditions. Up to the 50 percent load test, the PSU operated in fanless mode, and even when the fan engaged it did so at very low speeds and we had to actually overload the PSU to make the fan's speed exceed 1000 RPM. This is the most silent 750 W we have ever tested and we are pretty sure that this alone will be a key buying factor for many users.

You will find several screenshots of the Corsair Link software below, which we took during our test sessions.

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