Corsair CX450 PSU Review: Two Flavors, Tested and Compared

Efficiency, Temperature & Noise


We detail our efficiency testing procedure here.

Using results from the previous page, we plotted a chart showing the CX450’s efficiency at low loads and loads from 10 to 110 percent of its maximum-rated capacity.

Great Wall's platform was more efficient under normal and light loads.

Efficiency at Low Loads

In the following tests, we measured the CX450'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 20W, 40W, 60W and 80W. This is important for symbolizing when a PC is idle with power saving features turned on.

Corsair CX450 - Great Wall

Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed
PSU Noise
PF/AC Volts
11.197A0.499A0.478A0.198A19.53568.672%1105 RPM
24.0 dB(A)
22.455A0.999A0.990A0.397A39.92880.127%1100 RPM24.0 dB(A)0.948
33.649A1.495A1.472A5.032A59.42083.556%1170 RPM26.1 dB(A)0.969
44.910A1.997A1.982A0.796A79.83485.380%1235 RPM27.7 dB(A)0.979

Efficiency under light loads was very high, especially for a mainstream 450W unit.

Corsair CX450 - CWT

Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed
PSU Noise
PF/AC Volts
11.211A0.493A0.483A0.196A19.68664.915%818 RPM
13.8 dB(A)0.930
22.448A0.980A0.999A0.391A39.74476.855%818 RPM13.8 dB(A)0.976
33.685A1.478A1.514A5.064A59.86380.657%818 RPM13.8 dB(A)0.983
44.915A1.974A1.998A0.791A79.78082.976%818 RPM13.8 dB(A)0.988

CWT's fan spun at a lower RPM (revolutions per minute), but the PSU's efficiency levels weren't as high as Great Wall's implementation.

5VSB Efficiency

The ATX specification (revision 1.4), along with CEC, ErP Lot 3 2014 and ErP Lot 6 2010/2013, states that 5VSB standby supply efficiency should be as high as possible, recommending 75 percent or higher with 550mA, 1A and 1.5A of load. The PSU should also achieve higher than 75 percent efficiency at 5VSB under full load, or with 3A if its max current output on this rail is higher than 3A.

We took six measurements: one each at 100mA, 250mA, 550mA, 1,000mA and 1,500mA and one with the full load the 5VSB rail can handle.   

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

Great Wall's CX450 had a highly efficient 5VSB rail.

Power Consumption in Idle and Standby

The table below shows the power consumption and voltage values of all rails (except -12V) when the PSU was idle (powered on, but without any load on its rails) and the power consumption when the PSU was in standby mode (without any load, at 5VSB).

Mode12V5V3.3V5VSBWattsPF/AC Volts

The power consumption of both CX450s was very low at idle.

Fan RPM, Delta Temperature & Output Noise

We describe our mixed noise testing in detail here.

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

The next chart shows the cooling fan's speed in RPM and output noise. We measured acoustics from one meter away inside a hemi-anechoic (anechoic means non-echoing) chamber. Background noise inside the chamber was below 6 dB(A) during testing (it's actually much lower, but our sound meter’s microphone his its floor). We obtained the results with the PSU operating at 37°C (98.6°F) to 47°C (116.6°F) ambient temperature. 

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 30°C (86°F) to 32°C (89.6°F). 

CX450 (Great Wall)CX450 (Great Wall)

Great Wall's CX450 wasn't particularly quiet, as you can see in the graph above. With 150W of load, the noise output was greater than 30 dB(A). Above 270W, it exceeded 40 dB(A).

CX450 (Channel Well Technology)CX450 (Channel Well Technology)

CWT's CX450 had a much more relaxed fan profile. Up until 200W, its fan spun at low RPM. Even in a worst-case scenario, the noise output remained below 40 dB(A).

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