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Efficiency, Temperature & Noise
Efficiency
Our efficiency testing procedure is detailed here.
Using results from the previous page, we plotted a chart showing the 850 B3's efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.
Naturally, the 850 B3 doesn't stand a chance against higher-efficiency platforms. But compared to Thermaltake's lower-end SPR-0850F-R, the EVGA 850 B3 leads under normal and light loads.
Efficiency At Low Loads
In the following tests, we measure the 850 B3'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 | PSU Noise | PF/AC Volts |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1.200A | 0.493A | 0.478A | 0.192A | 19.629 | 62.453% | 0 RPM | <6.0 dB(A) | 0.834 |
| 12.141V | 5.052V | 3.315V | 5.130V | 31.430 | 115.18V | ||||
| 2 | 2.428A | 0.987A | 0.994A | 0.391A | 39.749 | 75.220% | 0 RPM | <6.0 dB(A) | 0.933 |
| 12.137V | 5.050V | 3.313V | 5.121V | 52.844 | 115.18V | ||||
| 3 | 3.662A | 1.477A | 1.508A | 5.110A | 59.870 | 78.364% | 0 RPM | <6.0 dB(A) | 0.937 |
| 12.133V | 5.048V | 3.312V | 5.110V | 76.400 | 115.18V | ||||
| 4 | 4.881A | 1.985A | 1.990A | 0.781A | 79.789 | 80.384% | 0 RPM | <6.0 dB(A) | 0.951 |
| 12.129V | 5.047V | 3.310V | 5.099V | 99.260 | 115.18V |
As expected, the efficiency we measured under light loads is very low. The only good thing we can say is that the fan doesn't spin, so noise is minimal.
5VSB Efficiency
The ATX specification, along with CEC, ErP Lot 3 2014 and ErP Lot 6 2010/2013, states that 5VSB standby supply efficiency should be as high as possible, recommending 75 percent or higher with 550mA, 1A, and 1.5A of load. The PSU should also achieve higher than 75% efficiency at 5VSB under full load, or with 3A if its max current output on this rail is higher than 3A.
We take six measurements: one each at 100, 250, 550, 1000, and 1500mA, and one with the full load the 5VSB rail can handle.
| Test # | 5VSB | DC/AC (Watts) | Efficiency | PF/AC Volts |
|---|---|---|---|---|
| 1 | 0.101A | 0.520 | 67.708% | 0.058 |
| 5.138V | 0.768 | 115.15V | ||
| 2 | 0.252A | 1.291 | 74.238% | 0.125 |
| 5.133V | 1.739 | 115.16V | ||
| 3 | 0.542A | 2.776 | 76.727% | 0.227 |
| 5.123V | 3.618 | 115.16V | ||
| 4 | 1.002A | 5.116 | 77.917% | 0.326 |
| 5.107V | 6.566 | 115.16V | ||
| 5 | 1.502A | 7.643 | 78.245% | 0.385 |
| 5.090V | 9.768 | 115.16V | ||
| 6 | 3.001A | 15.097 | 76.790% | 0.465 |
| 5.031V | 19.660 | 115.16V |
We would like to see higher efficiency levels on this rail.
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 | 12.143V | 5.052V | 3.316V | 5.140V | 10.501 | 0.500 |
| 115.2V | ||||||
| Standby | 0.125 | 0.010 | ||||
| 115.1V |
We measure increased vampire power with both voltage inputs. This partially explains the low efficiency at 5VSB under light loads.
Fan RPM, Delta Temperature, And Output Noise
Our mixed noise testing is described in detail here.
The chart below illustrates the cooling fan's speed (in RPM), and the delta between input and output temperature. The results were obtained at 37°C (98.6°F) to 46°C (114.8°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 hemi-anechoic chamber. Background noise inside the chamber was below 6 dB(A) during testing (it's actually much lower, but our sound meter’s microphone hits its floor), and the results were obtained with the PSU operating at 37°C (98.6°F) to 46°C (114.8°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).
EVGA's passive operation is frequently interrupted in order to keep the PSU's internal temperature under control.
With around 490W at +12V, our noise measurements exceed 30 dB(A), while with over 600W they fall within the 35-40 dB(A) range. Finally, it takes more than 730W at +12V to make the fan spin fast enough to generate >40 dB(A).
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