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Is there a problem with having too big a PSU?

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June 27, 2012 2:34:49 PM

Through a combo deal, I was able to get a very cheap 1000W PSU. I know this is too much for my current build -- everyone has recommended 750 or 800 -- but are there any disadvantages to using the bigger one? Will it use more electricity as a baseline, or will it only use as much as it needs?

Thanks!!

More about : problem big psu

a c 76 ) Power supply
June 27, 2012 2:40:54 PM

Other than the "very cheap" part of it not sounding too promising, no, there's no problem with having more (or even much more) than you need. It won't hurt anything and will only use as much as the system needs, but it'll probably just be a little less efficient than one closer to what you actually need because you'll be running it under its "butter zone".
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June 27, 2012 2:47:06 PM

DJDeCiBeL said:
Other than the "very cheap" part of it not sounding too promising, no, there's no problem with having more (or even much more) than you need. It won't hurt anything and will only use as much as the system needs, but it'll probably just be a little less efficient than one closer to what you actually need because you'll be running it under its "butter zone".



Thanks so much!
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a c 76 ) Power supply
June 27, 2012 2:49:36 PM

You're welcome. :) 
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a c 147 ) Power supply
June 27, 2012 3:09:35 PM

Very cheap is not a good idea for buying a psu. A cheap psu will not deliver it's advertised power, and a failure can damage anything it is attached to.
Exactly what brand and model are you talking about?

A psu operates most efficiently in the middle third of it's range. Since it only uses what is demanded, over provisioning is not a big deal.

1000w psu's are usually big. By that, I mean longer than normal. In some cases, this can be a problem.

Another drawback is that 1000w psu's will have more power leads than you can use, so cable management becomes more of an issue.

If the unit is a top quality unit, go for it . If it is a poor quality unit, abandon it.
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a b ) Power supply
June 27, 2012 3:29:12 PM

I see geofelt posed while I was SLOWLY typing, BUT totally aggree

First off. I don't think any regualar members recommend buying a case/PSU combo - UNLESS the PSU model is known and it is a "GOOD" PSU.
There are a Number of the "Bundled" PSU that should NEVER be used in a computer - best used as a door stop to prop the dorr open.
A LOW END PSU - You have a high risk of the PSU failing and taking OUT your MB, CPU, GPU and or Hard drives.

To answer your direct question, No you can always use a "larger" PSU than is needed. But that needs to be qualified.

The statement " The PSU will only use what is needed" is GENERALLY correct, But not always. The Computer will ONLY require what it Needs, But the PSU has a effiency rating so Total Power at the wall is based on 1) What the computer needs and 2) what the PSU itself consumes.
Recommended size of PSU for best eff. is from 20 % to 80 % of Listed power.
Generally no problem as 80 % of 1000 is 800 Watts. Most systems will be under this.
The problem is at Idle. 20% of 1000 is 200 Watts and Most new system draw less than this when NOT gaming. The eff goes down and the PSU losses go up - More electricity than what a properly sized PSU would use.

You say 750->800 Watt PSU is recommended. I've No idea as System is not listed, But generally on a new system anything over 650 Watts is overkill UNLESS you are runing a pair of High end GPUs in SLI or crossfire.
Example My i5-2500K OCed to 4.2 GHz with a 6870 GPU.
Idle is around 150 Watts and With a FULL load is only 350 Watts.
Based on that a 450 Watt would be MIN size and a QUALITY 550 would be great. I have a 650 Watt corsar TX PSU.
At idle this is 23% of rated Power - GOOD as over the 20%
At Full Load, is 54 % of rated power - ALSO Great as Under the 80% (My self I use 60->70% to determine upper end or Max size)
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