Power Usage of PC

[rubberduck]

Hi

Was just wondering about something.... If I have a computer that runs happily on a 400W PSU, If I upgraded my PSU to a 1000W would the cost to run the PC in terms of electricity go up? I would assume that there would be little increase as although the new PSU is capable of of 1000W only 400w is being used. Right?

Another thing. If a computer needs say 400W to run at 100% i.e. cpu and graphics card being stressed to the max, will it's power requirements drop when it is idling in windows and not doing anything? Or will it continue to draw 400w?

 

[Confused]

Most modern PSUs are switching - meaning they'll only provide what's being requested - plus of course the overheads for conversion from 240V AC to xV DC.

Additionally - power supplies are most efficient when running close to their maximum capacity - meaning less losses/overheads.

It could be marginally better to run it on the 400W PSU, running @ 90% capacity, providing it's providing the current that the components require, than getting a 1000W PSU, and having it run @ only 35% capacity, where it is not as efficient.

 

[mattyfez]

Your PC will only draw what it needs, so it will draw a lot less wordprocessing than it will playing a game.

However, PSU's do have sweet spots regarding efficiency, for arguments sake well say that sweet spot is between 40-80% load.

so a pc that is only capable of drawing 400w, will be more efficient with a 500w PSU than it will be with a 2000w PSU

 

[hp7909]

Watts stated/advertised are normally peak & most PSUs can not sustain that 24/7/365.

As mentioned, the PSUs will be more efficient according to how much your PC needs

 

[rubberduck]

Thanks for the answers... Generally how much less power does a PC use when it is idling compared to when it is running at its maximum? Would it be around 50%?

 

[hp7909]

It varies & also depends on different factors which include other components, speed throttling/power saving technology, etc. But, I'd say about 35% less