Efficiency

Using the results we gathered so far, we plotted a chart showing the PSU's efficiency at low loads and loads ranging from 10 to 110 percent of the maximum-rated capacity.




The UD750GM is more efficient than the P750GM in three of the four graphs, losing only by a bit in the 40–100 W load range.

10–110 % Load Testing

These tests reveal the PSU's load regulation and efficiency levels under high ambient temperatures and show how the fan-speed profile behaves under harsh operating conditions.


These tests are tough because I run them at high temperatures while pushing the PSU beyond its official ratings, at 110% load. I didn't encounter any problems, but the fan only spun at low speeds or not at all in the CL1 to CL3 tests despite high temperatures. This is not good for the PSU's long-term reliability, especially as users will be able to reproduce such usage scenarios frequently.

Light-Load Testing

We measure the PSU's efficiency at loads significantly lower than 10 percent of the maximum capacity—the lowest load the 80 PLUS standard measures. This is important for when a PC is idle with its power-saving features turned on.


The cooling fan doesn't spin at light loads, even at high ambient temperatures.

Super-Light Load Testing

We measure the PSU's efficiency with a 10 W load if its maximum power is 500 W or less in the following tests. If the PSU is stronger, we apply 2% of its maximum-rated-capacity load.


The PSU exceeds 60% efficiency with 2% load, but cannot surpass the 70% mark, which is recommended, but not required.

5VSB Efficiency

The 5VSB rail has decent efficiency.

Power Consumption in Idle and Standby

I would like to see 0.1 W vampire power or lower with 230 V input.