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 ERV650SWT's efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.
The efficiency that this platform achieves is on par with the competition. Under light loads, Enermax takes the lead from competition in the same 80 PLUS tier.
Efficiency At Low Loads
In the following tests, we measure the efficiency of Enermax's ERV650SWT 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 | 1.202A | 0.492A | 0.481A | 0.196A | 19.695 | 69.263% | 1155 RPM | 19.9 dB(A) | 0.881 |
| 12.164V | 5.050V | 3.328V | 5.045V | 28.435 | 115.13V | ||||
| 2 | 2.429A | 0.989A | 0.990A | 0.396A | 39.806 | 79.813% | 1200 RPM | 20.4 dB(A) | 0.948 |
| 12.157V | 5.047V | 3.323V | 5.039V | 49.874 | 115.13V | ||||
| 3 | 3.657A | 1.477A | 1.505A | 5.033A | 59.877 | 84.505% | 1300 RPM | 21.5 dB(A) | 0.965 |
| 12.150V | 5.042V | 3.320V | 5.033V | 70.856 | 115.13V | ||||
| 4 | 4.877A | 1.985A | 1.989A | 0.796A | 79.830 | 86.434% | 1390 RPM | 22.7 dB(A) | 0.960 |
| 12.145V | 5.039V | 3.316V | 5.028V | 92.360 | 115.13V |
The small fan spins even with 20W load because of the ambient temperature we test at, which comes close to 36°C.
During the last two tests, the PSU's efficiency easily exceeds the 80% mark. We'd like to see over 70% efficiency during the first test, though.
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 under full load, or with 3A if its maximum current output at 5VSB 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 | 0.510 | 75.893% | 0.066 |
| 5.019V | 0.672 | 115.14V | ||
| 2 | 0.252A | 1.264 | 80.356% | 0.141 |
| 5.016V | 1.573 | 115.14V | ||
| 3 | 0.542A | 2.718 | 81.769% | 0.243 |
| 5.011V | 3.324 | 115.14V | ||
| 4 | 1.002A | 5.016 | 82.081% | 0.327 |
| 5.004V | 6.111 | 115.14V | ||
| 5 | 1.502A | 7.503 | 81.991% | 0.373 |
| 4.995V | 9.151 | 115.14V | ||
| 6 | 3.002A | 14.922 | 80.782% | 0.435 |
| 4.971V | 18.472 | 115.13V |
The 5VSB rail is highly efficient, allowing the ERV650SWT to easily take first place.
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 | 12.244V | 5.050V | 3.331V | 5.048V | 8.230 | 0.486 |
| 115.1V | ||||||
| Standby | 0.082 | 0.004 | ||||
| 115.1V |
Vampire power is low with 115V and a little higher than expected with 230V.
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.
Next, we show 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 6.0 dB(A) during testing, and the results were obtained with the PSU operating at 37°C (98.6°F) to 46°C (114.8°F) ambient temperature. Thanks to our newly acquired Brüel & Kjær Type 4955a mic, we are able to perform low-noise measurements with great accuracy.
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).
Under very light loads, the fan's noise is minimal. And noise remains low at loads of up to 180W. But with more than 330W, the PSU's fan starts to make its presence felt. Beyond 460W, the fan profile goes crazy and our measurements land in the 40-45 dB(A) range.
MORE: Best Power Supplies
MORE: How We Test Power Supplies
MORE: All Power Supply Content
Windows 11 Mixed Reality support revived for Meta Quest 3, Quest 3S headsets
Kickstarter campaign claims its $39 AI-powered PlayStation 5 add-on reduces exhaust temps by up to 9 degrees C
Nvidia, AMD, and Intel all invest in light-based communication networks powering next-gen chips — Ayar Labs gets $155 million in funding
