Efficiency

Using the efficiency results from the previous page, we plotted a chart of the HPT750M's efficiency at low loads and loads equal to 20%-100% of the PSU's maximum-rated load.



The HPT750M is very efficient overall under both light and normal loads.

Efficiency at Low Loads

In the next tests, we measured the efficiency of the HPT750M at loads much lower than 20% of its maximum-rated load (the lowest load the 80 Plus Standard measures). 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.

At light loads, efficiency is nothing less than amazing. As you can see, there is no semi-passive operation, and the fan's minimum RPM could be much lower under such light loads.

5VSB Efficiency

The ATX specification and CEC, ErP Lot 3 2014, and ErP Lot 6 2010/2013 state 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 its 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 another with the full load the 5VSB rail can handle.

This is one of the most efficient 5VSB circuits we have taken measurements of so far! FSP has done wonders with this circuit.

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 kept low. With 115V input, it is even lower.

Fan RPM, Delta Temperature and 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 38-45 °C ambient.



A chart that shows the cooling fan's speed (RPMs) and its 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 is below 6.0 dBA during testing, and the results are obtained with the PSU operating at ambient temperatures of 38-45 °C.



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.



As has already been stated, there is no semi-passive mode, although an icon on its box tells us differently. The lack of a semi-passive operation is clearly shown in the graph above.