PSU getting warm: is it normal?

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Rafael Mestdag

Rafael Mestdag

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Mar 25, 2014
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Even when my pc is in idle the psu gets warm when I touch the top of the case(I know it should be on the bottom of the case) and it gets quite hot when gaming for more than 10 minutes or so.

It's a 500W unknown brand psu and the official site claims it is 70% efficient. Is it the reason why it's getting so hot? My graphics card doesn't go past 60 ºC and my cpu rarely goes over 55ºC when gaming.

This is my rig:

CPU: AMD FX 6300
Video: GTX 1050 2GB
HD: SSD Kingston 120GB + WD 500GB 5400 Rpm + Samsung 1TB SATA II 7200rpm
Motherboard: Gigabyte GA-LMT78-S2
RAM: 8GB RAM DDR3
PSU: 500 Watts

The strange thing is that when I put a normal big fan beside the open case pointing toward the psu, it gets cool and stays that way. But as soon as I remove the fan from the side of the case, it starts to get warm again.

Is there a chance this is normal?
 
Solution
InvalidError
More power dissipation in the PSU due to low efficiency = more heat coming out. By modern standards, 70% is extremely poor. 85% (half as much loss as your PSU around 50% load) is more typical of a modern decent quality entry-level PSUs.
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Titan
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May 18, 2007
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More power dissipation in the PSU due to low efficiency = more heat coming out. By modern standards, 70% is extremely poor. 85% (half as much loss as your PSU around 50% load) is more typical of a modern decent quality entry-level PSUs.
 
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Rafael Mestdag

Rafael Mestdag

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Mar 25, 2014
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So theoretically, even though this is a low quality psu, I don't need to worry or put a normal big fan pointing toward the psu?
 
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GhislainG

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Jul 16, 2008
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Heat isn't an issue, but a cheap PSU that fails could also take other components with it.

 
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InvalidError

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Titan
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May 18, 2007
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Since electrolytic capacitors' lifespan is closely related to their operating temperature and capacitors are the main component stopping the PSU from sending 20V ripples on the 12V rail, heat is indirectly the primary cause of PSU failure.

Of course, proper PSU layout and ventilation to keep capacitors happy is of limited use when the PSU has craptacular quality capacitors which play a significant role in the poor efficiency.
 
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Titan
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Poor quality PSUs don't need to be anywhere near full load to fail catastrophically. Some of those gutless wonders self-destruct before 50% load and they don't get any better with aging under high internal temperature.
 
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GhislainG

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I know all that, but the OP wanted to know if he could still use it and the answer is "yes". He has been warned about the risks, etc. I've seen a large number of cheap PSUs in business systems and they rarely fail. As long as it's a real 500W PSU and not a 300W unit labelled as 500W, then he can use it. Personally I wouldn't keep it for long, but unfortunately some people do have a limited budget.
 
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Titan
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May 18, 2007
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The chances of a 70%-efficient PSU being a legit 500W of any sort of quality are very low. I wouldn't be surprised if it happened to be a flyback topology and flyback isn't practical much beyond 100W due to the horrible ripples it shoves through its capacitors.

For OP's sake, I hope I am wrong about the PSU topology as flyback is the most likely to fry everything it is connected to as the topology has no intrinsic upper limit to how high output peaks can go after the capacitors fail. I've seen that happen on the 5VSB rail of many devices (including ATX PSUs) as nearly all AC-DC converters under 50W are still flyback.
 
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GhislainG

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Jul 16, 2008
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I presume the OP got that cheap PSU because of budget limitations. It would be helpful if he could post a picture of the sticker that provides details about the amperes on each rail; that would help us determine if it's a real 500W PSU or not (I agree with you that it probably isn't).
 
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Titan
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May 18, 2007
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Ratings printed on the PSU are useless as generic PSUs lie about them all the time and there are legitimate 500W PSUs with power distributions that make no sense in today's 12V-centric PCs. The brand and model number are far more useful.

As for being on a budget, that isn't much of an excuse when PSUs from Seasonic's S12-II series can often be had for under $40 which will last several years longer and save you 10-15% on your PC's power bill in the meantime. Depending on how bad OP's PSU is, you may also need to factor in the cost of replacing other components when the PSU dies and fries them.

Buying crappy PSUs is a false economy. Penny-wise, pound-foolish.
 
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