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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 VPF650 efficiency at low loads, and loads from 10 to 110 percent of the PSU's maximum-rated capacity.
Efficiency is pretty low by today's standards, under both light and normal loads. However, you can't be very picky about efficiency when it comes to inexpensive PSUs. At least this one will be very reliable thanks to the Japanese caps that it is equipped with.
Efficiency At Low Loads
In the following tests, we measure the efficiency of the VPF650 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(%) | Fan NoisedB(A) | PF/AC (V) |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1.200A | 0.481A | 0.472A | 0.195A | 19.60 | 62.32 | 910 | 30.1 | 0.934 |
| 12.138V | 5.112V | 3.379V | 5.105V | 31.45 | 115.1V | ||||
| 2 | 2.429A | 0.969A | 0.975A | 0.390A | 39.70 | 73.26 | 910 | 30.1 | 0.965 |
| 12.133V | 5.104V | 3.381V | 5.097V | 54.19 | 115.1V | ||||
| 3 | 3.664A | 1.466A | 1.476A | 0.585A | 59.84 | 77.71 | 910 | 30.1 | 0.970 |
| 12.127V | 5.098V | 3.382V | 5.088V | 77.00 | 115.1V | ||||
| 4 | 4.884A | 1.963A | 1.949A | 0.785A | 79.77 | 78.93 | 910 | 30.1 | 0.974 |
| 12.119V | 5.092V | 3.383V | 5.079V | 101.06 | 115.1V |
Efficiency at low loads is nothing to write home about, and as you can see from the table above, the unit doesn't manage to pass the 80 percent mark in any of the four tests we conducted. At least the fan's noise was kept at low levels, despite the high ambient temperature inside our hot box.
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 | 73.24% | 0.116 |
| 5.112V | 0.71W | 115.1V | ||
| 2 | 0.252A | 1.29W | 78.18% | 0.217 |
| 5.107V | 1.65W | 115.1V | ||
| 3 | 1.002A | 5.09W | 79.16% | 0.338 |
| 5.082V | 6.43W | 115.1V | ||
| 4 | 3.002A | 15.05W | 75.55% | 0.392 |
| 5.014V | 19.92W | 115.1V |
The 5VSB rail's performance was close to other units with similar capacity, so we have nothing to complain about.
Power Consumption In Idle And Standby
| Mode | 12V | 5V | 3.3V | 5VSB | Power (AC) | PF/AC Volts |
|---|---|---|---|---|---|---|
| Idle | 12.151V | 5.115V | 3.377V | 5.115V | 7.38W | 0.663 |
| 115.1V | ||||||
| Standby | 0.07W | 0.011 | ||||
| 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 is very low, and without a doubt this helps the PSU achieve decent efficiency during our 5VSB tests.
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 36 °C (96.8 °F) to 46 °C (114.8 °F) ambient temperature.
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 the PSU's 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 46 °C (114.8 °F) ambient temperature.
The following chart 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 °C (82.4 °F) and 30 °C (86 °F).
Under up to around 300W of load, the PSU operates quietly. With increased load levels, however, the fan's noise quickly exceeds 45 dB(A). The low overall efficiency of this design leads to significant thermal loads, hence the fan profile cannot be relaxed.
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