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Does Power Supply wattage affect cpu temp?

16230 Views 16 Replies 10 Participants Last post by  NicksTricks007
When i had my old 200W stock PSU, my AMD processor ran hot at around 65C. As soon as i upgraded to my 850 Antec PSU, my processor ran at 35-40 C. Was the temperature affected by my low watt crappy PSU?
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It shouldn't be affected by the wattage, no, since the PSU will only put out what is needed.

It is voltage that matters when it comes to heat, and that is regulated by the BIOS.
 

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A well-regulated PSU can reduce stress on the motherboard's VRM. The VRM don't have to work as hard filtering and stepping down the voltage. However, that wouldn't account for a 20-30C difference in temperature.
 

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You might of been over stressing the old PSU making it run hot and the new one is barely under load so will run nice and cool... (not too mention it will probably have better fans and be clean)...
 

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The wattage itself doesn't matter, but if you were badly stressing the PSU then it may have been giving too high/low voltage, which would cause the voltage regulation circuits on the motherboard and graphics card to have to work harder and generate more heat.
 

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Quote:

Originally Posted by TheReaperWaits View Post
You might of been over stressing the old PSU making it run hot and the new one is barely under load so will run nice and cool... (not too mention it will probably have better fans and be clean)...

That doesn't account for CPU temps. Even if the old PSU was 60% efficent, the heat dump wouldn't account the temp changes.

Quote:

Originally Posted by Phaedrus2129 View Post
The wattage itself doesn't matter, but if you were badly stressing the PSU then it may have been giving too high/low voltage, which would cause the voltage regulation circuits on the motherboard and graphics card to have to work harder and generate more heat.
That wouldn't account for a 30C difference though....

Swap the old PSU back and check temps again?
 

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Maybe it was overvolting on the +12V rail? I've seen +12V readings of 12.3V or higher causing components to overheat, though I thought the motherboard's voltage regulation was supposed to fix the voltage as it reached the board.
 

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Quote:

Originally Posted by Phaedrus2129 View Post
Maybe it was overvolting on the +12V rail? I've seen +12V readings of 12.3V or higher causing components to overheat, though I thought the motherboard's voltage regulation was supposed to fix the voltage as it reached the board.
ATX specs allow the voltage to be up to +12.6v so the VRM's should be able to handle that. The VRMs are suppose to stepdown the voltage to .9-1.6v (depending on CPU, of course). So 11.4-12.6v still should be converted to the same voltage to the CPU. Since the CPU is getting the same voltage, its temps shouldn't rise (but the VRMs might).
 

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Wattage has nothing to do with CPU temp, your PSU supplies wattage as needed.

Sounds like your old PSU was pushing out unstable/high voltage.
 

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Quote:

Originally Posted by Megaman_90 View Post
Sounds like your old PSU was pushing out unstable/high voltage.
Read above.

CPU gets the same voltage since the VRM filter and steps down the input voltage. Current is dependent on the CPU's draw. Therefore, the CPU's current, voltage, and wattage should all be relatively consistent and hence would not account for a 30C increase.
 

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Quote:

Originally Posted by DuckieHo View Post
Read above.

CPU gets the same voltage since the VRM filter and steps down the input voltage. Current is dependent on the CPU's draw. Therefore, the CPU's current, voltage, and wattage should all be relatively consistent and hence would not account for a 30C increase.
Yeah your probably right, 30C decrease is verging on ridiculous.

Maybe it was just a stuck sensor?
 

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I don't see simply switching a psu attributing to lower/raising heat to that degree. As said before, vcore is regulated before it hits the cpu from the psu, so it can't be that. It sounds like faulty sensor and/or monitoring application to me. Unless, when you switched the PSU, you happened to clean the CPU HSF and it was absolutely 100% covered in dust bunnies before. I suppose that could cause a pretty big difference, but I'm not sure even that would cause 30 degrees difference.
 

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Quote:


Originally Posted by DuckieHo
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ATX specs allow the voltage to be up to +12.6v so the VRM's should be able to handle that. The VRMs are suppose to stepdown the voltage to .9-1.6v (depending on CPU, of course). So 11.4-12.6v still should be converted to the same voltage to the CPU. Since the CPU is getting the same voltage, its temps shouldn't rise (but the VRMs might).

I see what you're saying, though I think the ATX specs are looser than they need to be; 11.7V and lower causes GPU instability, 12.3V and higher I know causes GPU overheating. I guess most GPUs' VRM isn't as efficient as the mobo's.
 

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Discussion Starter · #15 ·
I agree with the fact that my old PSU sucked. It was stock 200W. I was under the assumption that low watt and high voltage would increase temperatures. I can't think of any other reason why i would drop 30C immediately. While my new Antec supply has a bigger fan and better control, i don't think that would account for 30C.

I've just always wondered why i dropped so much in temp. I used to push 75-80C under load now i barely hit 50 (keep in mind i'm on AMD processor that runs hotter than Intel).
 

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Quote:

Originally Posted by Sun View Post
Or maybe the new PSU was simply better at removing heat? A better/larger fan goes a very long way, especially in an OEM type situation.
This is the only plausible explanation I can think of.
 

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I'm not sure a new PSU would account for that big of a temp difference either. But if you are stressing the PSU to its maximum capacity, that would definitely cause it to run much hotter which would in turn cause your temps inside the case to go up. And if all there is is hot air flowing inside the case, temps will definitely be affected. By how much, I'm not exactly sure, but......... I am willing to test this out if I can find an old PSU that works.
 
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