Question about PSU power usage

storm45 · 29 Nov 2015 at 22:33

Hi,

I've got an old gaming PC which has a Corsair Enthusiast Series TX 750W V2 High Performance Power Supply, I don't use this PC for gaming now and instead use it as a server for Plex and all my media storage.

My question is, if I were to get a 'Green' 350W PSU will there be a difference in power consumption as the PC/Server is on 24/7. Or does the 750W PSU use only the power consumed by the attached components?

I hope this makes sense and any help would be much appreciated.

Thanks

BlackBat · 29 Nov 2015 at 23:35

"the 750W PSU use only the power consumed by the attached components"

This.

storm45 · 29 Nov 2015 at 23:35

Ah ok cool, thanks for the quick reply

Threepwood · 30 Nov 2015 at 00:26

If the 350W psu is more efficiant than the 750W psu, then you would consume less power though.

If the PSU you are talking about is the superflower golden green, that is gold rated (+90% efficiancy) with your current 750W psu being bronze rated (80% efficiancy).

So, yes... There would be a difference in power consumption.

storm45 · 30 Nov 2015 at 00:29

oh ok. You're right I was talking about the superflower, I just don't know if its worth the change. Do you think it would make a big difference considering the PC/Server is on 24/7?

thanks

lee32uk · 30 Nov 2015 at 00:46

Threepwood said:
If the 350W psu is more efficiant than the 750W psu, then you would consume less power though.

If the PSU you are talking about is the superflower golden green, that is gold rated (+90% efficiancy) with your current 750W psu being bronze rated (80% efficiancy).

So, yes... There would be a difference in power consumption.

There is 5% difference between Bronze and Gold, as Bronze is 85% efficient at half load.

storm45 · 30 Nov 2015 at 00:53

thanks for the info, I think for now I'll stick with the 750w as there isn't a huge difference.

appreciate all your help guys

Mr Evil · 4 Dec 2015 at 17:43

lee32uk said:
There is 5% difference between Bronze and Gold, as Bronze is 85% efficient at half load.

The difference can be much larger at low load where most machines spend most of their time. For instance when I was choosing a PSU for a server which idles at about 30W, I saw that the best PSUs were about 75% efficient there, while others were only 50%. Still not worth replacing a PSU for.

Tealc · 6 Dec 2015 at 15:24

The additional cost of the slightly more efficient PSU would take years to recoup, even at 24hr usage.

On a typical 100W load and with 5% difference you'd only save £5 a year.

Generally it is never worth shelling out on additional efficiency, unless you are making a massive change ie from 70% efficiency to 90% and consume lots of energy.