Efficiency

Using the efficiency results from the previous page, we plotted a chart showing the efficiency of the BF750F at low loads and at loads equal to 20%-100% of the PSU's maximum-rated load.



With normal loads, the registered efficiency is satisfactory, but we would like to see readings that are 1-2 % higher with light loads.

Efficiency at Low Loads

We measured the efficiency of the BF750F at loads much lower than 20% of its maximum-rated load (the lowest load the 80 Plus Standard measures) in these tests. The loads we dialed were 40 W, 60 W, 80 W, and 100 W (for PSUs with a capacity of over 500 W). This is important for settings where the PC is in idle mode with Power Saving turned on.

A score over 80% in the first test would be nice.

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, among other things, 75% or higher efficiency with 550mA, 1A, and 1.5A of load. The PSU should also achieve more than 75% efficiency at 5VSB with full load, or with 3A if its maximum current output on the rail is higher than 3A.

We will take six measurements: one at 100, 250, 550, 1000, and 1500 mA, and one with the full load the 5VSB rail can handle.

The 5VSB rail's efficiency levels are good enough. However, we would like to see a reading closer to 80% in the last two tests.

Power Consumption in Idle & Standby

In the table below, you will find the power consumption and voltage values of all the rails (except for -12V) when the PSU is in idle mode (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).

Vampire power is pretty low.

Fan RPM, Delta Temperature & Output Noise

The cooling fan's speed (RPMs) and the delta difference between input and output temperature are illustrated in the following chart. The following results were obtained at 37-46 °C ambient.



A chart that shows the cooling fan's speed (RPMs) and output noise follows. We measure the fan's noise from a meter away, inside a hemi-anechoic chamber. Background noise inside the hemi-anechoic chamber was below 6.0 dBA during testing, and the results were obtained with the PSU operating at 37-46 °C ambient.



The following graph illustrates the fan's output noise throughout the PSU's entire operating range. The same conditions of the above graph apply to our measurements, but the ambient temperature was in between 30 °C and 32 °C.



Under normal operating temperatures, you won't hear the fan spin at up to around 410W of load. You will have to apply more than 600W at +12V in order to force the PSU's fan to reach 25-30 dB(A).