Why you can trust Tom's Hardware Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.
Efficiency, Temperature & Noise
Efficiency
Our efficiency testing procedure is detailed here.
Using results from the previous page, we plotted a chart showing the PR-BP0650-SM's efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.
The Onyx 650 takes the lead from its main competitor, Corsair's CX650M, based on a CWT platform (at least the one we reviewed last year).
Efficiency At Low Loads
In the following tests, we measure the PR-BP0650-SM'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 | DC/AC (Watts) | Efficiency | Fan Speed | Fan Noise | PF/AC Volts |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1.212A | 0.493A | 0.478A | 0.195A | 19.632 | 67.263% | 1460 RPM | 32.1 dB(A) | 0.884 |
| 12.021V | 5.036V | 3.326V | 5.077V | 29.187 | 115.12V | ||||
| 2 | 2.457A | 0.990A | 0.990A | 0.390A | 39.770 | 78.481% | 1470 RPM | 32.2 dB(A) | 0.940 |
| 12.014V | 5.034V | 3.323V | 5.071V | 50.675 | 115.14V | ||||
| 3 | 3.692A | 1.487A | 1.506A | 5.064A | 59.839 | 83.202% | 1490 RPM | 32.4 dB(A) | 0.971 |
| 12.019V | 5.030V | 3.319V | 5.064V | 71.920 | 115.14V | ||||
| 4 | 4.927A | 1.988A | 1.989A | 0.790A | 79.766 | 85.048% | 1510 RPM | 32.5 dB(A) | 0.970 |
| 12.013V | 5.026V | 3.315V | 5.055V | 93.789 | 115.15V |
Riotoro's fan spins at high speeds under light loads, proving once again that the programmed profile is very aggressive. Observed efficiency during the first two tests is quite low, but things get better in the remaining two tests where we get >80% readings.
5VSB Efficiency
The ATX specification, 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 | 0.102A | 0.517 | 76.935% | 0.061 |
| 5.086V | 0.672 | 115.15V | ||
| 2 | 0.252A | 1.280 | 79.751% | 0.135 |
| 5.083V | 1.605 | 115.15V | ||
| 3 | 0.543A | 2.754 | 80.385% | 0.239 |
| 5.077V | 3.426 | 115.15V | ||
| 4 | 1.002A | 5.078 | 80.221% | 0.328 |
| 5.066V | 6.330 | 115.15V | ||
| 5 | 1.502A | 7.591 | 79.914% | 0.377 |
| 5.054V | 9.499 | 115.16V | ||
| 6 | 3.002A | 15.068 | 77.887% | 0.443 |
| 5.020V | 19.346 | 115.15V |
The 5VSB rail achieves good efficiency overall. Corsair's CX650M does score higher in this discipline, though. CWT pays a lot of attention to its 5VSB circuit, after all.
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 | 12.055V | 5.040V | 3.329V | 5.085V | 13.111 | 0.664 |
| 115.1V | ||||||
| Standby | 0.047 | 0.223 | ||||
| 115.2V |
We measure very low vampire power with both voltage inputs.
Fan RPM, Delta Temperature, And Output Noise
Our mixed noise testing is described in detail here.
The 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 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 much lower, but our sound meter’s microphone hits its floor), and the results were 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 was between at 30°C (86°F) to 32°C (89.6°F).
Even under more realistic conditions (30-32°C ambient), the PSU's fan profile doesn't relax. With a load greater-than 200W, the fan's noise is between 30-35 dB(A), while anything higher than 340W puts it in the 35-40 dB(A) range.
MORE: Best Power Supplies
MORE: How We Test Power Supplies
MORE: All Power Supply Content
