Does a 1000W PSU use more electricity than a 650W PSU (same brand, same components plugged in)

45ACP

n00b
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Nov 1, 2016
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My current rig really only needs about 650W. But if I get a 1000W for future proofing, does it waste more electricity? I don't really care about the PSU cost, I just don't want to waste electricity because my electric bill keeps going up. (90% increase year over year because of some 'clean energy tax')
 

GoldenTiger

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Running a psu in its sweet spot will be more efficient, so no, it will not use more power. It will actually use less power. Generally around 50 to 70 percent load is ideal. You also will have lower noise levels and heat from not being up against the wall of your psu wattage. Finally, yes, it's a good idea for future proofing too :).
 

vegeta535

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Running a psu in its sweet spot will be more efficient, so no, it will not use more power. It will actually use less power. Generally around 50 to 70 percent load is ideal. You also will have lower noise levels and heat from not being up against the wall of your psu wattage. Finally, yes, it's a good idea for future proofing too :).
That is really not true with newer PSU anymore. The effecency curve is more flat across the upper load limits. You are losing like 5% at most from "optimum" load vs near full load. This is you actually buy a quality PSU. For instance my Super flower Platinum stays in doesn't drop below 90% between 25-100% load. To answer OP question. The difference will be negligible.
 
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pendragon1

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no. your component will draw what they draw, it can provide more, thats all. yeah there might be a slight efficacy diff but youd probably need special equip just to try and find it.
 

LukeTbk

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The PSU will get from the wall what it need to power your computer, so the total possible watt is not what matter it is how many watt the 650W PSU vs the 1000W use to power say your in average under load 400 watt system.

a 650 watt PSU efficancy curve can look like that:
efficiency.jpg


a 1000 watt can look like that:
corsair-rmx-series-1000-w-review-efficiency-tem.jpg


The one that will use the less electricity is the one with the highest % at your Watt usage.

For those 2 example, on 230V at 400 watt the RM1000x is around 93% the Be Quiets at 92.x%, almost the same.

Has you see and pointed out just above, efficiency does not drop that much at the highest load (the Y axis make it look bigger than it is), often now PSU goes from 91.8% peak efficiency at 40% load to 89-88% near 100% load, very similar.

And has you see both start to be really efficient at 200w despite the difference in maximum power, which limit even more the interest in trying to choose between them for electricity cost reason.

In general, if you future-proof by getting a larger Watt or a better PSU of similar Watt you will not consume more electricity, possibly it will be even a little less.
 
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Tsumi

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As said, it really depends. You will most likely lose a few % in efficiency in the idle range, but likely gain half a percent or so at load. Sure, you will lose a few %, but nominally the numbers are minimal (3% of 100 watts is less than 1% of 500 watts). It most likely comes out to be a wash, so if you have serious plans of going to a 800-900 watt setup in the near future, you may as well get the 1000w PSU now.

The thing you should not do is oversize the PSU to run at "max efficiency". You will lose efficiency at idle which would eat up most, if not exceed, the savings at load.
 

Nenu

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There can be a slight difference but nothing to worry about.
I always oversize my PSU and one PC is kept running 24/7.
However, I buy 80+ Gold to Titanium class PSUs (higher efficiency) running on 240V, this is worth observing.
https://en.wikipedia.org/wiki/80_Plus
 

N4CR

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Depends on efficiency curve of the PSUs and load.
It's not always clear cut.
 

pug71

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Apr 24, 2005
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I don't do that future proof crap. I buy for the gpu Im using at that period of time. when I upgrade I might buy another psu if need be. But no way in heck would I ever use some trash psu ever for my high end systems... not in 20 plus years. You see to many sad stories of peoples systems dying to bad psu's.
 
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