Efficiency

Using the efficiency results from the previous page, we plotted a chart showing the efficiency of the NEX750G 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 NEX750G 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.


At low loads, efficiency is satisfactory and the fan's speed is kept low. Nothing more to ask for here, especially if we take into account that this platform doesn't utilize cutting-edge technology.

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.


The 5VSB rail managed to surpass the minimum allowed efficiency levels on all tests, although it wasn't able to come close to or even pass the 80% mark.

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 any load at 5VSB).


Vampire power is low and makes the PSU compatible with the ErP Lot 6 2013 directive that will come into effect soon.

Fan RPM, Delta Temperature and Output Noise

The cooling fan's speed (RPMs) along with the delta difference between input and output temperature are illustrated in the following chart. The following results were obtained at 40°C - 45°C ambient.



The Delta difference is small since the PSU's heatsinks are small and because they don't dissipate that much heat.

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.



The fan isn't that quiet, even at low RPM. This makes the PSU unsuitable to users with sensitive hearing.