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Efficiency, Temperature & Noise


Our efficiency testing procedure is detailed here.

Using results from the previous page, we plotted a chart showing the TX750M's efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.

The TX750M's efficiency is satisfactory, however it is no match for higher-end EVGA G3 and Corsair RM750x models. Our average efficiency graph shows the entire TX-M family finishing in order of highest to lowest capacity, with the TX850M on top.

Under light loads, though, the opposite is true...

Efficiency At Low Loads

In the following tests, we measure the TX750M's efficiency at loads significantly lower than 10 percent of its maximum capacity (the lowest load the 80 PLUS standard measures). The loads we dialed were 20, 40, 60, and 80W. This is important for representing when a PC is idle, with power-saving features turned on.

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Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan SpeedFan NoisePF/AC Volts
11.209A0.491A0.482A0.196A19.68465.899%1190 RPM28.0 dB(A)0.893
22.444A0.990A0.990A0.392A39.82478.949%1220 RPM28.5 dB(A)0.964
33.676A1.477A1.499A5.060A59.86482.695%1230 RPM29.2 dB(A)0.980
44.899A1.986A1.981A0.789A79.80485.551%1240 RPM29.6 dB(A)0.987

The fan spins at high speeds, even under very light loads. In the first test, we'd like to see closer to 70% (or better) efficiency.

5VSB Efficiency

The ATX specification states that 5VSB standby supply efficiency should be as high as possible, recommending 50 percent or higher with 100mA of load, 60 percent or higher with 250mA of load, and 70 percent or higher with 1A or more of load.

We take four measurements: one each at 100, 250, and 1000mA, and one with the full load the 5VSB rail can handle. 

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Test #5VSBDC/AC (Watts)EfficiencyPF/AC Volts

The 5VSB rail is highly efficient. As far back as we can remember, all of the Corsair PSUs we've tested fare well in this discipline.

Power Consumption In Idle And Standby

In the table below, you'll find the power consumption and voltage values of all rails (except -12V) when the PSU is idle (powered on, but without any load on its rails), and the power consumption when the PSU is in standby mode (without any load, at 5VSB).

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Mode12V5V3.3V5VSBWattsPF/AC Volts

Vampire power is very low, facilitating high efficiency on the 5VSB rail (especially under light loads).

Fan RPM, Delta Temperature, And Output Noise

Our mixed noise testing is described in detail here.

Our first chart illustrates the cooling fan's speed (in RPM), and the delta between input and output temperature. The results were obtained at 37°C (98.6°F) to 47°C (116.6°F) ambient temperature.   

The next chart shows the cooling fan's speed (again, in RPM) and output noise. We measured acoustics from one meter away, inside a hemi-anechoic chamber. Background noise inside the chamber was below 16.6 dB(A) during testing. It's actually quite a bit lower, but our sound meter's mic is at its limit there. The ambient temperature was between 37°C (98.6°F) and 47°C (116.6°F). 

The following graph illustrates the fan's output noise over the PSU's operating range. The same conditions of the above graph apply to our measurements, though the ambient temperature was between at 30°C (86°F) to 32°C (89.6°F).  

Under normal temperatures, the PSU's fan doesn't make much noise until ~450W load. Even with 100W more, it stays below 31 dB(A). And in a worst-case scenario it doesn't exceed 34 dB(A). The fan profile is optimized for ~30°C ambient, though. Anywhere above 35-36°C, it starts to get really aggressive.

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Contributing Editor

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

  • NinjaNerd56
    I have one of the 'sister' versions of this PSU. I like it a lot. My case is all air cooled, so I never hear the fan on the Corsair.
  • Dom_79
    So I guess this is a "re-release" of the TX-xxxM semi-modular line?


    I have one of these ^ sitting in a box somewhere. Not that bad a unit but I hope they don't go through another "V2" fiasco with thise new line. If memory serves, the last time the issue was attributed to using a newer OEM manufacturer...

    Great review though! Very thorough and well presented :)
  • Nuckles_56
    Thanks for the review Aris, it looks like with a few tweaks, this platform could really kill it
  • mrmez
    Got a TX-750w 9 years ago.
    Still going great!
  • Dark Lord of Tech
    Any chance to review the new CX series released by Corsair recently. Not the M , but the non modular CX.
  • superninja12
    I needed this review , thank you :D