Efficiency (low load)
It is important to look at the efficiency of the power supplies. The higher the efficiency, the less energy is wasted when converting 230 volts to 12, 5 and 3.3 volts. We tested the efficiency of every power supply at 22.5 watts, 50 watts, 100 watts and from there in steps of 100 watts all the way up to the maximum that the power supply can offer. It is often at low loads that power supplies perform the least efficient.
Looking at the average efficiency at loads up to 100 watts - basically when your PC is idle or when you are performing simple tasks like browsing the web or editing texts - we see global scores that range from 70% to 80% efficiency, where the Corsair CX750M has the lowest score with 72.7%. The best scores are achieved by the Seasonic Prime Titanium power supplies: both of them have an efficiency that is more than 87%.