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Efficiency
Our efficiency testing procedure is detailed here.
Using results from the previous page, we plotted a chart showing the HX750’s efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.
With normal loads the HX750 takes over the third place, while with light loads it is away from the highly efficient Aerocool ACP-750FP7, which is based on Andyson's Titanium platform.
Efficiency At Low Loads
The ATX specification (revision 1.4), along with CEC, ErP Lot 3 2014 and ErP Lot 6 2010/2013, states that the 5VSB standby supply efficiency should be as high as possible, recommending 75 percent or higher with 550mA, 1A, and 1.5A of load.
The supply should also achieve higher than 75% efficiency at 5VSB under full load, or with 3A if its max current output on this rail is higher than 3A.
We take six measurements: one each at 100, 250, 550, 1000, and 1500mA, and one with the full load the 5VSB rail can handle.
| Test # | 12V | 5V | 3.3V | 5VSB | DC/AC (Watts) | Efficiency | Fan Speed (RPM) | PSU Noise (dB[A]) | PF/AC Volts |
| 1 | 1.213A | 0.493A | 0.481A | 0.196A | 19.635 | 68.556% | 0 | <6.0 | 0.840 |
| 12.024V | 5.023V | 3.305V | 5.019V | 28.641 | 115.14V | ||||
| 2 | 2.457A | 0.990A | 0.998A | 0.396A | 39.782 | 81.006% | 0 | <6.0 | 0.931 |
| 12.018V | 5.021V | 3.305V | 5.013V | 49.110 | 115.14V | ||||
| 3 | 3.700A | 1.487A | 1.508A | 5.008A | 59.878 | 84.421% | 0 | <6.0 | 0.954 |
| 12.012V | 5.020V | 3.305V | 5.008V | 70.928 | 115.14V | ||||
| 4 | 4.933A | 1.996A | 1.995A | 0.796A | 79.826 | 86.872% | 0 | <6.0 | 0.969 |
| 12.007V | 5.019V | 3.305V | 5.005V | 91.889 | 115.14V |
With 20W load it would be great to see over 70% efficiency. On the rest three tests the 80% mark is easily passed.
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% efficiency at 5VSB under full load, or with 3A if its max current output on this rail is higher than 3A.
We take six measurements: one each at 100, 250, 550, 1000, and 1500mA, and one with the full load the 5VSB rail can handle.
| Test # | 5VSB | DC/AC (Watts) |
Efficiency | PF/AC Volts |
| 1 | 0.101A | 0.513 | 76.682% | 0.065 |
| 5.058V | 0.669 | 115.15V | ||
| 2 | 0.252A | 1.272 | 79.649% | 0.147 |
| 5.055V | 1.597 | 115.16V | ||
| 3 | 0.542A | 2.738 | 80.648% | 0.270 |
| 5.049V | 3.395 | 115.16V | ||
| 4 | 1.002A | 5.050 | 80.363% | 0.387 |
| 5.039V | 6.284 | 115.16V | ||
| 5 | 1.502A | 7.552 | 80.187% | 0.453 |
| 5.029V | 9.418 | 115.15V | ||
| 6 | 3.002A | 14.998 | 78.941% | 0.522 |
| 4.996V | 18.999 | 115.14V |
FSP's unit achieves the first place here with a major difference from the second entry, which belongs to the HX750.
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).
| Mode | 12V | 5V | 3.3V | 5VSB | Watts | PF/AC Volts |
| Idle | 12.028V | 5.023V | 3.304V | 5.023V | 8.214 | 0.464 |
| 115.2V | ||||||
| Standby | 0.045 | 0.005 | ||||
| 115.2V | ||||||
The phantom power levels are low, with both 115V and 230V input.
Fan RPM, Delta Temperature, And Output Noise
Our mixed noise testing is described in detail here.
The first chart below 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 46°C (114.8°F) ambient temperature.
The next chart shows the cooling fan's speed (again, in RPM) and output noise. We measure acoustics from one meter away, inside a hemi-anechoic chamber. Background noise inside the chamber is below 6 dB(A) during testing (it's actually much lower, but our sound meter’s microphone hits its floor), and the results are obtained with the PSU operating at 37°C (98.6°F) to 46°C (114.8°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 is between 30°C (86°F) to 32°C (89.6°F).
Once you push the minor rails the semi-passive operation is not engaged. This is something that we have noticed in other CWT implementations as well.
