Efficiency, Temperature, And Noise
Efficiency
Our efficiency testing procedure is detailed here.
Using results from the previous page, we plotted a chart showing the 850 G3's efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.
This is one of the most efficient PSUs in the Gold-rated 850W category. Super Flower built a top-notch successor to the original Leadex Gold platform.
Efficiency At Low Loads
In the following tests, we measure the 850 G3's efficiency at loads significantly lower than 10 percent of its 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 | DC/AC (Watts) | Efficiency | Fan Speed | Fan Noise | PF/AC Volts |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1.210A | 0.501A | 0.478A | 0.197A | 19.69 | 74.106% | 0 RPM | 0 dB(A) | 0.743 |
| 12.065V | 4.989V | 3.315V | 5.095V | 26.57 | 115.07V | ||||
| 2 | 2.445A | 1.000A | 0.996A | 0.390A | 39.79 | 78.830% | 1645 RPM | 44.4 dB(A) | 0.875 |
| 12.070V | 4.989V | 3.315V | 5.092V | 50.47 | 115.07V | ||||
| 3 | 3.678A | 1.496A | 1.507A | 5.086A | 59.86 | 83.104% | 1555 RPM | 43.2 dB(A) | 0.924 |
| 12.077V | 4.991V | 3.316V | 5.086V | 72.03 | 115.07V | ||||
| 4 | 4.901A | 2.004A | 1.990A | 0.786A | 79.77 | 85.165% | 1565 RPM | 43.5 dB(A) | 0.947 |
| 12.074V | 4.991V | 3.316V | 5.080V | 93.66 | 115.08V |
Under light loads, the 850 G3 achieves good efficiency. However, its passive mode is really brief, after which the fan spins at high speeds. During the second test, the fan spins more quickly than in the other two tests to quickly exhaust heat from the PSU's internals.
5VSB Efficiency
The ATX specification states that 5VSB standby supply efficiency should be as high as possible, recommending 50 percent or higher with 100mA of load, 60 percent or higher with 250mA of load, and 70 percent or higher with 1A or more of load.
We take four measurements: one each at 100, 250, and 1000mA, and one with the full load the 5VSB rail can handle.
| Test # | 5VSB | DC/AC (Watts) | Efficiency | PF/AC Volts |
|---|---|---|---|---|
| 1 | 0.101A | 0.515 | 66.796% | 0.057 |
| 5.098V | 0.771 | 115.11V | ||
| 2 | 0.251A | 1.279 | 74.145% | 0.120 |
| 5.094V | 1.725 | 115.11V | ||
| 3 | 1.002A | 5.087 | 78.322% | 0.308 |
| 5.077V | 6.495 | 115.11V | ||
| 4 | 3.002A | 15.073 | 76.876% | 0.442 |
| 5.021V | 19.607 | 115.10V |
The 5VSB regulation circuit needs a redesign to enable higher efficiency. It is a shame to see the 850 G3's 5VSB rail demonstrate mediocre performance when the PSU fares so well in the other disciplines we've looked at so far.
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 the PSU is in standby mode (without any load, at 5VSB).
| Mode | 12V | 5V | 3.3V | 5VSB | Watts | PF/AC Volts |
|---|---|---|---|---|---|---|
| Idle | 12.063V | 4.989V | 3.316V | 5.103V | 8.346 | 0.432 |
| 115.1V | ||||||
| Standby | 0.142 | 0.011 | ||||
| 115.1V |
Standby power consumption is high with both voltage inputs.
Using230V input and registering close to 0.25W vampire power, the PSU was unable to achieve higher than 45% efficiency at 5VSB with 0.225W load, which is required by the ATX spec.
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 RPM), and the delta between input and output temperature. The results were obtained at 36°C (96.8°F) to 47°C (116.6°F) ambient temperature.
The next chart shows the cooling fan's speed (again, in RPM) and output noise. We measured acoustics from one 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 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 PSU's operating range. The same conditions of the above graph apply to our measurements, though the ambient temperature was between at 30°C (86°F) to 32°C (89.6°F).
As we've mentioned, EVGA's passive mode doesn't last for long. The fan profile is aggressive in general, and given the PSU's high efficiency, it could definitely be much more relaxed. Obviously EVGA wanted to stay on the safe side given its 10-year warranty.
