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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 V750's efficiency at low loads, and loads from 10 to 110 percent of the PSU's maximum-rated capacity.
Under low loads, efficiency is good. However, it cannot match the competition from Corsair and Seasonic. The situation improves with normal loads and the V750 takes fourth place in our chart, passing the Corsair RM750i and EVGA SuperNOVA 750 G2.
Efficiency At Low Loads
In the following tests, we measure the V750'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.
| Test # | 12V | 5V | 3.3V | 5VSB | Power(DC/AC) | Efficiency | Fan Speed | Fan Noise | PF/AC Volts |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1.198A | 0.491A | 0.476A | 0.195A | 19.60W | 69.09% | 585 RPM | 27.9 dB(A) | 0.883 |
| 12.147V | 5.041V | 3.348V | 5.035V | 28.37W | 115.1V | ||||
| 2 | 2.425A | 0.990A | 0.985A | 0.395A | 39.72W | 80.18% | 585 RPM | 27.9 dB(A) | 0.937 |
| 12.145V | 5.038V | 3.345V | 5.031V | 49.54W | 115.1V | ||||
| 3 | 3.657A | 1.476A | 1.495A | 0.594A | 59.81W | 84.50% | 585 RPM | 27.9 dB(A) | 0.961 |
| 12.141V | 5.036V | 3.341V | 5.024V | 70.78W | 115.1V | ||||
| 4 | 4.872A | 1.984A | 1.975A | 0.795A | 79.70W | 86.79% | 585 RPM | 27.9 dB(A) | 0.966 |
| 12.137V | 5.033V | 3.338V | 5.017V | 91.83W | 115.1V |
At under 100W loads, the PSU has good efficiency overall. Even under high ambient temperatures (close to 38 °C) the fan is almost inaudible, since it spins slowly.
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 take four measurements: one each at 100, 250 and 1000mA, and one with the full load the 5VSB rail can handle.
| Test # | 5VSB | Power (DC/AC) | Efficiency | PF/AC Volts |
|---|---|---|---|---|
| 1 | 0.101A | 0.50W | 66.67% | 0.064 |
| 4.931V | 0.75W | 115.1V | ||
| 2 | 0.251A | 1.24W | 70.46% | 0.143 |
| 4.925V | 1.76W | 115.1V | ||
| 3 | 1.002A | 4.91W | 79.45% | 0.338 |
| 4.899V | 6.18W | 115.1V | ||
| 4 | 2.501A | 12.12W | 79.27% | 0.453 |
| 4.846V | 15.29W | 115.1V |
With 115V input, the 5VSB rail had good enough efficiency (during the last two tests it was close to 80 percent). Again, the same can't be said for 230V; the impact on efficiency was huge.
Power Consumption In Idle And Standby
| Mode | 12V | 5V | 3.3V | 5VSB | Power (AC) | PF/AC Volts |
|---|---|---|---|---|---|---|
| Idle | 12.168V | 5.054V | 3.357V | 5.054V | 9.53W | 0.622 |
| 115.1V | ||||||
| Standby | 0.07W | 0.006 | ||||
| 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).
In standby, the V750 consumes only 0.07W, easily meeting the ErP Lot 6 2013 requirements.
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 (RPMs), and the delta between input and output temperature. The results were obtained between 36 °C (96.8 °F) and 48 °C (118.4 °F) ambient temperature.
The next chart shows the cooling fan's speed (RPMs) 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 anechoic chamber was below 18 dB(A) during testing, and the results were obtained with the PSU operating at 36 °C (96.8 °F) to 48 °C (118.4 °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).
As you can see, at normal operating temperatures, the V750 operates silently. Up at around 350W, the noise output is between 28-31 dB(A), and with 550W and more it increases to the 34-37 dB(A) region. Worst case, the output noise is around 40-43 dB(A).
