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.




Efficiency is satisfactory in the 10%–100% load range and very high in all other regions.

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.


The PSU copes well with high operating temperatures while fully loaded, and the fan-speed profile is highly relaxed at up to the 60% load test. I managed to force the fan to spin at its maximum RPM during only the full load and overload tests, where the ambient temperature is above 45°C.

Light Load Testing

In the following tests, 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.


Very high-efficiency levels under light loads.

Ultra-light Load Testing

The applied load in this test is only 10 W for PSUs with 500 W and less capacity. We dial in 2% of the maximum-rated capacity for all other PSUs and only run this test with 115 V input.


Intel asks for efficiency above 70% with 2% load, and the RM850x exceeds 77%. This is top performance!

5VSB Efficiency

The older RM850x model is slightly ahead here.

Power Consumption in Idle and Standby

Vampire power stays low with 230 V input.