Question Best PSU for a Low-Wattage Idle System ?

[jtyubv]

I have a server that is idle most of the time, but it always needs to be on. It has an i7-8700 on an Asus Prime Z390-A motherboard. I was experimenting with two PSUs I have and I was shocked to find a massive disparity in the idle power draw on the system, depending on which PSU I was using.

Using an "EVGA 550 BP, 80+ Bronze 550W" PSU, the system would idle at 25.2 watts. When I swapped that PSU with an "EVGA 600 GE, 80 Plus Gold 600W", the system would idle at 38.4 watts, over 13 watts higher! There weren't any other changes when measuring the difference besides simply swapping the PSU. I repeated it multiple times with the same observation.

Although I know higher wattage units are going to be less efficient at lower wattages in general, I did not expect this large of a difference, especially considering it is gold while the more efficient one was bronze.

This makes me wonder if it would be possible to get the idle power consumption down on this system a lot more by using even lower wattage PSUs; for example, might a 300 watt unit like this one reduce the idle power draw significantly more? I have the cpu power limited so the whole system never goes above 90 watts, so there would still be a good amount of distance to the 300W limit.

 

[4745454b]

I don't see a review for the EVGA 600 GE, 80 Plus Gold 600W. I saw some release articles dated April of this year so it's probably too soon for a trusted review? I did read it has an Eco mode, did you test under both modes?

 

[Misgar]

In all probabilty, you'd be operating the 300W PSU further up its efficiency curve, so you might draw less power, but unless you know its rating (Gold, Platinum, etc.,) it's difficult to tell if it will be better than your current PSU.