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 SuperNOVA 850 T2's efficiency at low loads, and loads from 10 to 110 percent of the PSU's maximum-rated capacity.
This is hands-down one of the most efficient (if not the most efficient) PSUs we have tested. It easily takes the lead from all other high-end offerings with similar capacity. Then again, we haven't tested any other 850W Titanium-rated power supplies, so our comparison data only includes Platinum- and Gold-rated models. Hopefully we start seeing more entries in this segment, though we're sure many of you would rather see Titanium-rated 400 to 600W PSUs for more mid-range builds.
Efficiency At Low Loads
In the following tests, we measure the efficiency of EVGA's SuperNOVA 850 T2 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 (RPM) | Fan Noise | PF/AC Volts |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1.193A | 0.490A | 0.479A | 0.194A | 19.64 | 74.71% | 0 | 0 dB(A) | 0.716 |
| 12.225V | 5.049V | 3.320V | 5.110V | 26.29 | 115.0V | ||||
| 2 | 2.413A | 0.989A | 0.992A | 0.391A | 39.78 | 84.16% | 0 | 0 dB(A) | 0.864 |
| 12.225V | 5.047V | 3.319V | 5.103V | 47.27 | 115.0V | ||||
| 3 | 3.633A | 1.475A | 1.505A | 5.099A | 59.83 | 87.64% | 0 | 0 dB(A) | 0.918 |
| 12.225V | 5.043V | 3.318V | 5.099V | 68.27 | 115.1V | ||||
| 4 | 4.840A | 1.983A | 1.988A | 0.785A | 79.76 | 89.50% | 0 | 0 dB(A) | 0.940 |
| 12.225V | 5.042V | 3.318V | 5.094V | 89.12 | 115.1V |
Under light loads the 850 T2 is highly efficient and dead silent. There's nothing more we could want.
5VSB Efficiency
he 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.Â
| Test # | 5VSB | DC/AC (Watts) | Efficiency | PF/AC Volts |
|---|---|---|---|---|
| 1 | 0.101A | 0.52 | 72.22% | 0.033 |
| 5.111V | 0.72 | 115.1V | ||
| 2 | 0.251A | 1.28 | 79.01% | 0.072 |
| 5.109V | 1.62 | 115.1V | ||
| 3 | 1.002A | 5.11 | 83.09% | 0.230 |
| 5.095V | 6.15 | 115.1V | ||
| 4 | 2.502A | 12.68 | 81.86% | 0.381 |
| 5.066V | 15.49 | 115.1V |
Super Flower finally decided to make some changes that lead to increased efficiency on the 5VSB rail. In the next upgrade of this circuit, the company should make it a little stronger as well, with at least 3A max current output.
Power Consumption In Idle And Standby
| Mode | 12V | 5V | 3.3V | 5VSB | Watts | PF/AC Volts |
|---|---|---|---|---|---|---|
| Idle | 12.246V | 5.050V | 3.322V | 5.118V | 5.99 | 0.253 |
| 115.1V | ||||||
| Standby | 0.11 | 0.005 | ||||
| 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 with both voltage inputs (115V/230V AC).
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 33 °C (91.4 °F) to 48 °C (118.4 °F) ambient temperature.  Â
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 33 °C (91.4 °F) to 48 °C (118.4 °F) ambient temperature.Â
The following graph 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 at 28 °C (82.4 °F) to 30 °C (86 °F). Â
Up to 548W of load (456W at +12V and 92W on the minor rails) the PSU operates passively, making zero noise. When the fan starts to spin, it keeps a steady rotational speed around 620 RPM. There, its output noise is close to 21 dB(A); the fan remains inaudible. This is the quietest PSU we've ever tested, excluding the completely passive ones, of course. The very high efficiency levels it achieves play a key role here, since there's little wasted thermal energy.