Efficiency, Temperature And Noise
Efficiency
Our efficiency testing procedure is detailed here.
Using the results from the previous tests, we plotted a chart showing the EVGA 550 G2 efficiency at low loads, and loads from 10 to 110 percent of the PSU's maximum rated capacity.
In this comparison, the 550 GS unit wins by a small margin in both low and normal loads. However, the 550 G2 PSU registers very high efficiency levels overall.
Efficiency At Low Loads
In the following tests, we measure the efficiency of the EVGA 550 G2 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 | 5V | 3.3V | 5VSB | Power(DC/AC) | Efficiency | Fan Speed | Fan Noise | PF/AC Volts |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1.186A | 0.491A | 0.480A | 0.194A | 19.60W | 73.77% | 0 RPM | 0 dBA | 0.811 |
| 12.254V | 5.065V | 3.315V | 5.102V | 26.57W | 115.1V | ||||
| 2 | 2.405A | 0.979A | 0.995A | 0.389A | 39.70W | 82.57% | 0 RPM | 0 dBA | 0.904 |
| 12.252V | 5.064V | 3.313V | 5.094V | 48.08W | 115.1V | ||||
| 3 | 3.624A | 1.476A | 1.509A | 0.588A | 59.85W | 86.13% | 0 RPM | 0 dBA | 0.952 |
| 12.250V | 5.062V | 3.311V | 5.084V | 69.49W | 115.1V | ||||
| 4 | 4.834A | 1.974A | 1.993A | 0.785A | 79.77W | 87.51% | 0 RPM | 0 dBA | 0.947 |
| 12.248V | 5.060V | 3.308V | 5.074V | 91.16W | 115.1V |
At low loads, efficiency is very high, and in three of the four tests we conducted, it easily passed the 80-percent mark. In addition, the PSU operated in passive mode throughout these tests, while the ambient temperature inside the hotbox was above 35 C (95 F).
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 | 0.101A | 0.52W | 71.23% | 0.108 |
| 5.108V | 0.73W | 115.1V | ||
| 2 | 0.251A | 1.28W | 75.74% | 0.209 |
| 5.103V | 1.69W | 115.1V | ||
| 3 | 1.002A | 5.09W | 78.43% | 0.374 |
| 5.077V | 6.49W | 115.1V | ||
| 4 | 3.001A | 14.90W | 76.61% | 0.466 |
| 4.966V | 19.45W | 115.1V |
Efficiency on the 5VSB rail was low, especially with the full load. We would like to see efficiency hitting close to, or even above, 80 percent in the last two tests.
Power Consumption In Idle And Standby
| Mode | 12 V | 5 V | 3.3 V | 5VSB | Power (AC) | PF/AC Volts |
|---|---|---|---|---|---|---|
| Idle | 12.267V | 5.068V | 3.316V | 5.111V | 6.23W | 0.534 |
| 115.1V | ||||||
| Standby | 0.10W | 0.016 | ||||
| 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).
In standby mode, power consumption is at low levels. As expected, with 230 VAC, it is a little higher, but it's still well below the 0.5W that the ErP Lot 6 2013 directive requires.
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 in rotations per minute (RPMs), as well as the delta between input and output temperatures. The results were obtained at 35 to 45 C (95 to 113 F) ambient temperature.
The second chart shows the cooling fan's speed and output noise. We measured acoustics from 1 meter (3 feet) away, inside a small, custom-made anechoic chamber with the internals of the PSU completely covered in sound-proofing material (be quiet! Noise Absorber kit). Background noise inside the anechoic chamber was below 18 dBA during testing, and the results were obtained with the PSU operating at 35 to 45 C ambient temperature.
The following chart illustrates the fan's output noise over the entire operating range of the PSU. The same conditions as those for the chart above apply to our measurements, though the ambient temperature was 28 to 30 C (82.4 to 86 F).
The semipassive mode doesn't last very long. However, we think this is good because, that way, sensitive components, like electrolytic capacitors, won't be exposed to tough conditions, which can significantly affect their life spans. After all, this PSU is equipped with a low-speed RPM fan, and in conjunction with the highly relaxed fan profile, even at full loads and normal temperatures, the fan's output noise doesn't exceed 37 dBA. This particular PSU is ideal for users who want to avoid noisy system components.
