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Efficiency, Temperature And Noise
Efficiency
Our efficiency testing procedure is detailed here.
Using the results from the previous page, we plotted a chart showing the 750 GQ's efficiency at low loads, and loads from 10 to 110 percent of the PSU's maximum-rated capacity.
Under light loads, the 750 GQ manages to match the higher-priced G2 model's performance; under normal loads, it trails a bit. Overall though, the GQ achieves good efficiency, especially if we take into account its affordable price.
Efficiency At Low Loads
In the following tests, we measure the efficiency of EVGA's 750 GQ 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.
| Test # | 12V | 5V | 3.3V | 5VSB | DC/AC (Watts) | Efficiency | Fan Speed (RPM) | Fan Noise (dB[A]) | PF/AC Volts |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1.202A | 0.501A | 0.482A | 0.195A | 19.66 | 72.68% | 0 | 0 dB(A) | 0.889 |
| 12.126V | 4.983V | 3.304V | 5.099V | 27.05 | 115.0V | ||||
| 2 | 2.435A | 0.999A | 0.999A | 0.391A | 39.78 | 82.70% | 0 | 0 dB(A) | 0.925 |
| 12.124V | 4.977V | 3.299V | 5.093V | 48.10 | 115.0V | ||||
| 3 | 3.664A | 1.496A | 1.515A | 5.089A | 59.81 | 86.26% | 0 | 0 dB(A) | 0.945 |
| 12.117V | 4.973V | 3.294V | 5.089V | 69.34 | 115.0V | ||||
| 4 | 4.891A | 2.013A | 2.003A | 0.785A | 79.82 | 87.90% | 0 | 0 dB(A) | 0.952 |
| 12.111V | 4.970V | 3.291V | 5.084V | 90.81 | 115.0V |
Under light loads, the PSU's fan doesn't spin and efficiency is pretty high (even down to 20W). Apparently the ACRF topology in this unit has low power losses, allowing for increased efficiency without the use of exotic and expensive parts.
5VSB Efficiency
The ATX specification states that 5VSB standby supply efficiency should be as high as possible, recommending 50 percent or higher efficiency with 100mA of load, 60 percent or higher with 250mA of load and 70 percent or higher with 1A or more of load.
We will take four measurements: one each at 100, 250 and 1000mA, and one with the full load the 5VSB rail can handle.
| Test # | 5VSB | DC/AC (Watts) | Efficiency | PF/AC Volts |
|---|---|---|---|---|
| 1 | 0.102A | 0.52 | 68.42% | 0.129 |
| 5.107V | 0.76 | 115.1V | ||
| 2 | 0.252A | 1.29 | 77.25% | 0.230 |
| 5.105V | 1.67 | 115.1V | ||
| 3 | 1.002A | 5.10 | 79.32% | 0.370 |
| 5.090V | 6.43 | 115.1V | ||
| 4 | 3.002A | 15.17 | 79.72% | 0.439 |
| 5.053V | 19.03 | 115.1V |
The 5VSB rail registers high enough efficiency levels, although it doesn't manage to pass the 80 percent mark in any test. It does get close under full load, however. In general, the performance of this rail is pretty good since it combines tight load regulation with increased efficiency.
Power Consumption In Idle And Standby
| Mode | 12V | 5V | 3.3V | 5VSB | Watts | PF/AC Volts |
|---|---|---|---|---|---|---|
| Idle | 12.148V | 4.982V | 3.304V | 5.112V | 7.41 | 0.708 |
| 115.1V | ||||||
| Standby | 0.15 | 0.028 | ||||
| 115.1V |
In the table above, 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).
Vampire power isn't as low as in other PSUs we have tested. Still, EVGA's 750 GQ passes the ErP Lot 6 2013 requirements with flying colors, 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 34 °C (93.2 °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 small, custom-made anechoic chamber with internals completely covered in sound-proofing material (be quiet! Noise Absorber kit). Background noise inside the chamber was below 18 dB(A) during testing, and the results were obtained with the PSU operating at 34 °C (93.2 °F) to 47 °C (116.6 °F) ambient temperature.
The following graph illustrates the fan's output noise over the entire operating range of the PSU. The same conditions of the above graph apply to our measurements, though the ambient temperature was between at 28 °C (82.4 °F) to 30 °C (86 °F).
The PSU started our tests with its fan spinning slowly, and not in passive mode as it should have been. More than likely, this was because we were pushing the minor rails right off the bat. Passive mode was triggered afterwards, but not for long. Up to around 350W load, the fan made a bit of noise. For a short time afterward, its speed increased, only to drop again between 400-450W. Beyond 500W, the noise levels increased quickly, and under 600W or more, the noise was very loud.
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