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Efficiency, Temperatures And Noise
Efficiency
Our efficiency testing procedure is detailed here.
Using the results from the previous page, we plotted a chart showing the efficiency of the SX500-LG at low loads and at loads equal to 10 to 110 percent of the PSU's maximum rated capacity.
If we take into account its compact form factor, which imposes some limitations, the SX500-LG fared well against its ATX competition. Compared to its SFX siblings, it was behind the SX600-G at normal loads. At light loads, however, it managed to take the lead. Although the difference in efficiency at normal loads with 230V input was significant, with 115V, the SX500-LG was slightly ahead (0.6 percent).
Efficiency At Low Loads
In the next tests, we measured the efficiency of the SX500-LG at loads significantly lower than 10 percent of the device's maximum capacity (the lowest load the 80 PLUS standard measures). The loads we dialed were 20, 40, 60 and 80W. This is important to represent when a PC is idle with power-saving features turned on.
| Test | 12V (A/V) | 5V (A/V) | 3.3V (A/V) | 5VSB (A/V) | Power DC/AC (W) | Efficiency (%) | Fan Speed (RPM) | Fan NoisedB(A) | PF/AC (V) |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1.187A | 0.480A | 0.472A | 0.195A | 19.60 | 72.17 | 600 | 24.2 | 0.917 |
| 12.258V | 5.119V | 3.373V | 5.127V | 27.16 | 115.0 | ||||
| 2 | 2.406A | 0.968A | 0.978A | 0.391A | 39.72 | 80.88 | 690 | 26.6 | 0.962 |
| 12.251V | 5.117V | 3.368V | 5.118V | 49.11 | 115.0 | ||||
| 3 | 3.628A | 1.459A | 1.485A | 0.586A | 59.87 | 85.24 | 725 | 26.9 | 0.979 |
| 12.245V | 5.113V | 3.363V | 5.107V | 70.24 | 114.9 | ||||
| 4 | 4.834A | 1.953A | 1.965A | 0.780A | 79.71 | 86.41 | 885 | 29.8 | 0.984 |
| 12.238V | 5.110V | 3.358V | 5.098V | 92.25 | 114.9 |
At low loads, efficiency was high, with three out of the four tests passing the 80 percent mark. In addition, the PSU was almost inaudible; it stayed below 30 dB even during the last test, which was conducted at an ambient temperature of close to 40 degrees C (104 degrees F).
5VSB Efficiency
The ATX specifications state that 5VSB standby supply efficiency should be as high as possible, recommending 50 percent or higher for a load of 100mA, 60 percent or higher for a load of 250mA and 70 percent or higher for a load of 1A or more.
We take four measurements: one each at 100mA, 250mA and 1000mA, along with the full load the 5VSB rail can handle.
| Test | 5VSB (A/V) | Power DC/AC (W) | Efficiency (%) | PF/AC (V) |
|---|---|---|---|---|
| 1 | 0.102A | 0.52 | 71.23 | 0.116 |
| 5.135V | 0.73 | 115.3 | ||
| 2 | 0.252A | 1.29 | 74.14 | 0.214 |
| 5.132V | 1.74 | 115.3 | ||
| 3 | 1.002A | 5.13 | 81.04 | 0.300 |
| 5.115V | 6.33 | 114.9 | ||
| 4 | 3.002A | 15.22 | 77.61 | 0.353 |
| 5.071V | 19.61 | 115.0 |
Although 115V efficiency on the 5VSB rail was pretty good, we cannot say the same for 230V. Nonetheless, the SX500-LG performed much better than the SX600-G, which has even smaller dimensions and thus is subject to more limitations.
Power Consumption In Idle And Standby
| Mode | 12V | 5V | 3.3V | 5VSB | Power (AC) | PF/AC Volts |
|---|---|---|---|---|---|---|
| Idle | 12.264V | 5.120V | 3.379V | 5.138V | 7.01W | 0.597 |
| 115.1V | ||||||
| Standby | 0.11W | 0.02 | ||||
| 115.4V |
In the table above, you can see the power consumption and voltage values of all of the 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 mode, the PSU consumes only 0.11W, and with 230V, the power consumption increases to 0.25W. That's still half of the maximum consumption set by the ErP Lot 6 2013.
Fan RPM, Delta Temperature And Output Noise
Our mixed noise testing is described in detail here.
The following chart illustrates the cooling fan's speed (RPMs), and the delta between input and output temperature. The results were obtained at an ambient temperature between 37 and 45 degrees C (99 to 113 degrees F).
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 soundproofing 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 an ambient temperature of 37 to 45 degrees C.
The following graph illustrates the fan's output noise over the PSU's entire operating range. The same conditions of the above graph apply to our measurements, but the ambient temperature was between 28 and 30 degrees C (82 to 86 degrees F).
At loads of up to about 250W, the PSU is dead silent, whereas with typical loads, it is about 28 to 31 dB. Therefore, its output noise most likely will be covered up by the noise of the rest of the system components. In a worst-case scenario under full load, the noise reaches about 40 dB, which is still low enough for a compact PSU with 500W of capacity.
