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 And Noise
Efficiency
Our efficiency testing procedure is detailed here.
Using the results from the previous page, we plotted a chart showing the ST1500-GS efficiency at low loads, and loads from 10 to 110 percent of the PSU's maximum-rated capacity.
Efficiency is low at both light and normal loads. Enhance stayed well behind the competition with this platform and will need to make many improvements to the design if it wants this PSU to stay in the game.
Efficiency At Low Loads
In the following tests, we measure the efficiency of the ST1500-GS 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 for representing 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) | PowerDC/AC(W) | Efficiency(%) | Fan Speed(RPM) | Fan NoisedB(A) | PF/AC (V) |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1.188A | 0.491A | 0.480A | 0.195A | 19.61 | 52.36 | 890 | 35.5 | 0.744 |
| 12.264V | 5.028V | 3.329V | 5.109V | 37.45 | 115.1V | ||||
| 2 | 2.406A | 0.989A | 0.990A | 0.391A | 39.72 | 62.35 | 890 | 35.5 | 0.878 |
| 12.260V | 5.025V | 3.326V | 5.100V | 63.71 | 115.1V | ||||
| 3 | 3.622A | 1.486A | 1.502A | 0.586A | 59.83 | 70.05 | 930 | 42.6 | 0.907 |
| 12.258V | 5.023V | 3.323V | 5.094V | 85.41 | 115.1V | ||||
| 4 | 4.830A | 1.994A | 1.985A | 0.785A | 79.78 | 74.19 | 1230 | 40.1 | 0.931 |
| 12.256V | 5.021V | 3.321V | 5.085V | 107.53 | 115.1V |
At light loads, efficiency was much lower than we expected. Surely a very high-capacity PSU has a great disadvantage at such low loads, but still it should offer better results, especially when compared with the performance of other PSUs in this category under the same conditions.
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 will 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 | 0.102A | 0.52W | 72.22% | 0.043 |
| 5.120V | 0.72W | 115.1V | ||
| 2 | 0.252A | 1.29W | 77.25% | 0.098 |
| 5.114V | 1.67W | 115.1V | ||
| 3 | 1.002A | 5.10W | 81.47% | 0.285 |
| 5.088V | 6.26W | 115.1V | ||
| 4 | 3.502A | 17.52W | 77.22% | 0.478 |
| 5.004V | 22.69W | 115.1V |
The 5VSB rail's efficiency performance was a very pleasant surprise. Enhance did a very good job with this circuit.
Power Consumption In Idle And Standby
| Mode | 12V | 5V | 3.3V | 5VSB | Power (AC) | PF/AC Volts |
|---|---|---|---|---|---|---|
| Idle | 12.269V | 5.030V | 3.334V | 5.123V | 13.70W | 0.392 |
| 115.1V | ||||||
| Standby | 0.11W | 0.007 | ||||
| 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).
Phantom power was quite low in both cases (115V and 230VAC input).
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 temperatures. The results were obtained at 38 C (100.4 Fahrenheit) to 47 C (116.6 F) ambient temperature.
The next chart shows the cooling fan's speed (RPMs) and output noise. We measured acoustics from 1 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 47 C (116.6 F) ambient temperature.
The following graph illustrates the fan's output noise over the operating range of the PSU. The same conditions of the above graph apply to our measurements, though the ambient temperature was between 28 C (82.4 F) and 30 C (86 F).
As you can see from the graph above, up to around 900 W load the ST1500-GS is quiet, which is true for all 1.5 kW PSUs that don't feature a semi-passive mode. At a load greater that 900 W, the noise output quickly increases to extremely loud levels, which in worst case scenarios exceed 49 dBA.
