SilverStone SX600-G SFX Power Supply Review

Efficiency, Temperatures And Noise

Efficiency

Using the previous page's results, we plotted a chart showing efficiency of the SX600-G at low loads and at loads equal to 10 percent to 105 percent of the PSU's maximum.

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As expected, the unit registers 2-2.5 percent higher efficiency with 230V than 115V. Simply put, this has to do with the fewer amperes required for the same amount of load, leading to lower energy losses. The SX600-G performs well in our efficiency calculations, even against larger 80 PLUS Gold-certified units. Its performance is especially great at low loads, rendering this PSU the ideal choice for a system with low-energy consumption at idle.

Efficiency At Low Loads

In the next tests, we measured the efficiency of the SX600-G at loads significantly lower than 10 percent of the device's maximum (the lowest load the 80 PLUS standard measures). The loads we dialed were 20, 40, 60 and 80 W. This is important for representing when a PC is idle with power-saving features turned on.

At only 20 W, efficiency drops below 70 percent. But in the other three tests it goes significantly higher, and during the last two low-load tests the 80 percent mark is easily broken. Due to the high operating temperature (above 34 °C), the semi-passive mode wasn't active. But the fan's noise wasn't annoying, either. Still, according to SilverStone, this PSU should be in passive mode until the internal temperature hits 45 °C, and we are pretty sure that at least during the 20 W load test, this threshold was not broken.

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 took four measurements: one each at 100, 250 and 1000mA, and one with the full load the 5VSB rail can handle. 

At 5VSB, the efficiency readings are average. We expected higher efficiency on this rail, especially from a Gold-rated unit.

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 it's in standby mode (without any load at 5VSB).

Power consumption at standby and with 115 V is significantly higher than 230 V input. However, it's still below 0.5 W, so this unit meets the ErP Lot 6 2013 requirements.

Fan RPM, Delta Temperature And Output Noise

The cooling fan's speed (RPMs), and delta between input and output temperature are illustrated in the following chart. The results were obtained at 34-45 °C ambient.   

At high operating temperatures, the fan speed comes close to 3600 RPM.

This 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 20 dB(A) during testing, and the results were obtained with the PSU operating at 34 to 45 °C ambient temperature. 

The noise can exceed 52 dB(A) if you stress the PSU like we did. It's definitely loud.

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 28 and 30 °C.

The above graph was made using data gathered while the PSU was operating at normal ambient temperatures, and it shows that passive mode lasts only for a short period. We are not surprised by this. In such a small PSU with restricted airflow, it would be dangerous to allow fanless operation under any significant load.