PSU at bottom of case?

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jaz2018

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Feb 19, 2018
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I'm looking at buying a new case and am seeing PSU's mounted at the bottom directly (apparnently) underneath video cards or Ram .... this doesnt make sense to me -

Does anyone have any comments on this?
 
Solution
Raiddinn
You don't want heat from the video card and processor to go into the PSU, that's the problem with top mounting.

In the past when PC components didn't generate heat in meaningful amounts, it didn't matter if you top mounted a PSU and used the PSU as a case fan.

Once PC components started generating large amounts of heat, that became a problem.

See, PSUs work much much worse at high temps than they do at low temps and rising heat from components is a big deal. PCs with top mount PSUs often have a problem where they shut down during gaming but they work fine every other time. That largely is due to the heat generated when the video cards are actually working hard. That's why it only happens during gaming. The PSU fan is good enough...
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Bottom mount PSU is very, very common. More cases are built like that than top mount.
Why would you think it is a problem?
 
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Hi
(Sorry I'm not sure how to quote a message here)

My concern is that PSU's get hot and heat rises.
Putting them directly underneath sensitive circuits just seems plain wrong
no matter how much cooling the PSU has.
Presumably you must also have extra cooling in the case itself just
to account for it.

Why would you put a heat source there?
 
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The PSU also has its own fan, to draw in cool air from outside, and expel it out the back.

If this were a "problem", cases wouldn't be designed like that.
 
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However they still get hot hence the fan - and placing them underneath circuitry is
going to increase the temperature of that circuitry.
(Put your hand on the top of one - be prepared to get burned though)

Just because there are a lot of them doesnt make it a good idea.


 
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Not "a lot of them"...rather "most of them".
If it were an issue, cases would not be designed like that.

"be prepared to get burned" ? I just checked one of my systems. Slightly warmer than ambient.
If yours gets that hot, maybe you have a defective unit.
 
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I've just bumped into 2 comments on cases about PSU's causing possible heat problems
(browsing amazon - not looking for such comment)
One was someone talking about overheating SSD's he has had to move

I dont KNOW its a problem - thats why I'm asking here but now I've seen comments suggesting
it may be - and it does make sense.

So far I have one comment that it is no problem - I await others with interest.

PS - I'm appreciative of your answer - I should say thank you. Sorry.

 
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1. I treat Amazon user reviews with large grains of salt.
2. "overheating SSD" is almost assuredly a surface mounted M.2 drive. A lot of those overheat anyway.

If the airflow inside the case were zero, yes, the (minimal) heat from the PSU would rise up and heat up some of the other components.
But, since in any rational case, the air is moving through it...front to back...that heat radiating off the top of the PSU case is of no consequence.
The air inside is in continual motion.

But I shall enlist other opinions.
 
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This depends on the PSU IMO. The right PSU will have a large fan on the bottom of it so that it can pull lots of cool fresh air inside it. This air cools off the components and the psu inner casing and gets expelled out the rear. I've had users put bottom mounted cases on carpet, which tends to block the airflow, as well as put old psu's in, ones with small fans on the rear, that do get a bit warm.

You will also need good case airflow for the rest of the pc. I usually only use ones with dual 120MM fan slots in the front.

I have had a bottom mounted PSU for years and even had my ssd's taped to the top of it for month while I waited for a specific mounting plate to get off of backorder. I had no issues even while gaming heavily.
 
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For "burning hot", I just tested mine with an IR thermometer.

Antec VP450 in the HTPC
Simultaneous:
Playing a movie out to the TV.
Copying 8GB data in from the NAS
Copying 10GB data out to the NAS

Ambient temp of 22C
PSU case temp of 25-26C.
 
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Many new PC cases have covers around the PSU area at bottom which I expect helps protect any components above them from any heat. Most of these covers are there just to hide PSU since almost all cases are glass sided now, but it still potentially helps the cooling. Most fans in PSU strong enough to extract the heat out of case anyway.

My case has top mounted PSU but then its designed to use the heat rising idea to cool PC. So many cases use the same designs inside, its hard to find anything unique now.
 
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Treat Amazon comments as if an idiot wrote them, because they probably are written by an idiot. a PSU thats that hot, is broken, or on fire. Likely there was some other issue that someone who literally doesn't know better attributed to the PSU.

Check out my Gaming PC (link in my signature), I have a lot of high temp components, and I have stuck my hand in there. Under a gaming load my GPU is astronomically hotter than the PSU.

And I'll do you one better, my PSU is actually set up passively, its flipped over, the vent is at the top and the fan is in hybrid mode. Most of the time the fan doesn't even turn on, the heat from the PSU goes into the case and is exhausted out with the rest of the heat. If its gets REALLY hot the fan does turn on and blows case air through the PSU.

You're really worrying about an issue thats not an issue.
 
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What I'm reading here is that covers protect the system from heat and fans are taking it away anyway.
Perhaps putting the PSU back at the top of the case would reduce the number of fans required?
 
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There are two reasons for a PSU being placed at the bottom; 1) better cooling and 2) better balance for a case as it puts a bulky item low down and hence lowers the overall CoG.

A bottom-mounted PSU can draw cool air directly from outside the case, over the internals and then back out. A top-mounted case can only draw warm air from inside the case - this will increase the ambient temp of the PSU and lead to a shorter lifespan.

A modern, good-quality PSU won't radiate much heat. They typically have efficiency ratings well north of 80-85% now, which means a minimal amount of the power drawn is wasted as heat. So that's not an issue. In terms of impact on other components, there are plenty of other heat sources inside a PC well in excess of the level of heat a PSU will radiate - primarily GPUs. Yes, mobo components are sensitive, but they're designed to work in a PC environment and the heat level associated with this. A good PSU won't appreciably contribute to this.

Now, cheaper PSUs may be different - they typically won't be as efficient, won't have the features of a good-quality PSU and may very well radiate more heat. But again, not very much. If a PSU is radiating significant heat, radiate that PSU right out of your system before it goes horribly wrong for you.

The vast majority of case manufacturers put PSUs on the bottom as it is seen as the best design option. In a competitive market, with an enthusiast audience who value low temps and high framerates, they will look for every advantage to make their product the one to buy. If placing a PSU elsewhere was a better option, we would see it coming through in case design.
 
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Many older systems were cooled only by the fan on the PSU drawing heat out through the top. That said a lot of today's equipment requires quite a bit more cooling than that, and so the PSU fan is inconsequential. Its something, and maybe it would eliminate 1 exhaust fan, but theres also all the insides of the PSU slowing airflow down, so its not necessarily the best way to cool your system.
 
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I should have stayed out of this thread. I am only making it worse.

Unlike 99% of cases made now, mine has all of its intake fans at bottom and expels the air out of top of case, hence why PSU is at top. See picture below for indication, the red thing in middle is the GPU, it stands horizontally in case and blows air out of top (the picture isn't an accurate picture of my PC, its from the Silverstone site)

5970_in_FT02.jpg


the bracket and opening at top right of picture is where my PSU is attached, its meant to suck cool air from back of case and blow it out top. I don't understand why more PC cases don't use this layout, though its not really designed for watercooling so there could be that reason;

For most PC, the PSU at base is good enough now.
 
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looking at todays cases I can only think the best description is "overkill" with knobs on.
I'll click something to close the thread and thank you all for the interest.
$150 dollars for a tin can with some bits of plastic and a couple of cheap fans?
seriously?
 
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I dont know where you get $150 from ??

Something really nice like a phanteks p400s is $70 , comes with $25 worth of fans included, has a tempered glass side panel , 3 speed fan controller , psu shroud & is excellent quality.

The most ive paid for a case is £70 uk which got me a discontinued fractal design r4 which is still one of the best made cases on the planet & once again comes with £30 worth of fans preinstalled.
 
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i like a nice looking case, if I have to look at it every day I don't want it to look cheap. I will admit I have spent too much on cases in the last few PC but I wanted the one I have now since I saw it 5 years ago.

I saw a video about my case and it answered one question in my above answer... the reason no one does it is it makes no difference. The output of 3 x 180mm fans cancels out any gain you get from rotating motherboard 90 degrees, and blowing air out top. they just stood my case on its front and proved it for themselves.

I don't mind, its still a very good air cooling case. Beats most new cases into ground in that regard, just lacks a few newer features.

[video="https://www.youtube.com/watch?v=otiIWhPKc20"][/video]

note: Raven RL02 & Fortress FT02 have the same internals, I have the fortress which is all aluminium and looks better than this one in video.
 
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