Efficiency

Using the efficiency results from the previous page, we plotted a chart showing the efficiency of the MK3S750 at low loads and at loads equal to 20-110% of the PSU's maximum-rated load.



For a discussion of these results, see the text at the end of the previous page.

Efficiency at Low Loads

In the next tests, we measured the efficiency of the MK3S750 at loads much lower than 20% of its maximum rated load (the lowest load that the 80 Plus Standard measures). The loads that we dialed were 40, 60, 80, and 100 W (for PSUs with over 500 W of capacity). This is important for settings where the PC is in idle mode with power saving turned on.


Efficiency at low loads is definitely not ground breaking, but it is still high enough, especially for the capacity and efficiency rating of the unit.

5VSB Efficiency

The ATX spec states that the 5VSB standby supply's efficiency should be as high as possible and recommends 50% or higher efficiency with 100 mA of load, 60% or higher with 250 mA of load, and 70% or higher with 1 A or more of load.

We will take four measurements: one at 100, 250, and 1000 mA each, and one with the full load that the 5VSB rail can handle.


Efficiency at 5VSB is only average and this is a shame. During the first two tests, the minimum allowed limit wasn't reached, and efficiency was below 75% on the last two tests.

Power Consumption in Idle & Standby

In the table below, you will find the power consumption and the voltage values of all rails (except -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 a load at 5VSB).


Phantom power is lower than 0.5 W, so the PSU is compliant with the new ErP Lot 6 2013 directive.

Fan RPM, Delta Temperature and Output Noise

The following chart illustrates the cooling fan's speed (RPMs) and the delta difference between input and output temperature. Results were obtained at 40°C - 45°C ambient.



A chart that shows the cooling fan's speed (RPMs) and the output noise follows. We measure the fan's noise from 1 meter away. The background noise in our lab was close to 30 dBA during testing.