Efficiency

Using the efficiency results from the previous page, we plotted a chart showing the efficiency of the MX650 at low loads and loads equal to 20%–100% of the PSU's maximum-rated load.



This is a very efficient PSU under both light and normal loads.

Efficiency at Low Loads

In the next tests, we measured the efficiency of the MX650 at loads much lower than 20% of its maximum-rated load (the lowest load the 80 Plus Standard measures). The loads we dialed in were 40 W, 60 W, 80 W, and 100 W (for PSUs with a capacity over 500 W). This is important for settings where the PC is in idle mode with Power Saving turned on.


With light loads, efficiency levels are pretty good! The low power factor readings are the only downside. With 115 V input, PF readings will be higher.

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 others, 75 percent 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 max current output on this rail is higher than 3A.

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


The efficiency of the 5VSB rail needs improvement. We would like to see a reading close to 80%.

Power Consumption in Idle and Standby

In the table below, you will find the power consumption and 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 very low, which improves 5VSB efficiency at very light loads.

Delta Temperature

The delta difference between input and output temperature is illustrated in the following chart. The following results were obtained at 34–40 °C ambient.