Top mounted Fan

jonnyGURU

Moderator <BR> Power Supplies
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Oct 30, 1999
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These days... that IS a typically located fan.

It's 120MM vs. 80MM and can move more air with a lower rotation speed, so it is quieter.

Also, to make sure you completely understand because you say it's a "top mounted fan", the fan points DOWN in most cases where the PSU is located at the top. It would only point up if you had one of the few "upside-down" cases on the market.
 

Navid

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Jul 26, 2004
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There is no reason to mount the PSU upside down (with the fan at the top).
A decent case, like Antec P180, has enough clearance under the PSU for enough intake cool air.
Cool air goes down. Warm air goes up. Always orient the PSU with its horizontal intake fan at the bottom.
 

mpilchfamily

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Jun 11, 2007
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Technicly there is no top or bottom of the PSU. It can be oriented in any manner and will not effect the performance of the unit. Many case now allow you to orient the PSU with either the fan facing up or down. So long as there is plenty of space for the fan to draw air in you are fine.
 

Navid

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Jul 26, 2004
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Originally posted by: mpilchfamily
So long as there is plenty of space for the fan to draw air in you are fine.

Think of a PSU with the fan at the top at the top of the case. No matter how much space there is at the top for air, that is where warm air accumulates (at the top of the case). Why would you want to orient your PSU that way to pull in all the trapped warm air over the PSU in that case?
 

jonnyGURU

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Actually, heat only rises if it's still. In other words, in a vacuum, yes. You wouldn't want to suck hot air in from the top.

But in a PC, you are constantly moving air with fans. Hot air never really gets to rise unless that's the way you have the air moving within your case.

The only "hot spots" in your PC are going to be those area close to devices that typically radiate heat. Your PC is not inherently hot on the top, cool on the bottom.
 

Navid

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Jul 26, 2004
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I used to have a case (Antec Super LANBOY) with the PSU mounted at the top.
I used to have a PSU with only an 80mm exhaust fan. Later I switched to a Seasonic PSU with an intake (PSU intake) fan at the bottom. I installed the PSU with the intake fan facing down.

My case exhaust fan was under the PSU like many other ATX cases.

In both cases, when under load, whenever I touched the top of my case from outside, it felt much warmer than the sides.
Considering that my case was metallic and a good thermal conductor, if the top of the case is warmer than the sides, the only thing that could cause that is the warm air. Please tell me if this is an erroneous conclusion.

Do you have any reason to believe that air would circulate at the top of the PSU at the top of the case with no fan on the top of the PSU and no fan at the top of the case (the case exhaust fan being under the PSU not over)?
Also, the case intake fan being at the bottom of the case. So, its air intake would not directly disturb the air above the PSU.

Edit:
I think your comment was with respect to my first post. :eek:

I agree 100%; warm air goes up and cold air goes down when there is no force other than gravity in play.
But, I still believe that warm air can get trapped over a PSU installed at the top of a case and installing the PSU with its intake fan at its top is not a good idea.
 

Zepper

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May 1, 2001
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They show the pic that way so you'll be impressed by the big fan normally the PSU will be mounted the other way up (with the fan on the "bottom". Properly designed PSU cooling is the ticket, not the size of the fan(s) or it's (their) location(s). You can mount the PSU in either orientation in the P180. Generally if the fan is to be aimed downward in a bottom PSU case, their will be a vent in the bottom of the case (I'd hope it would have some filter material over it). Mount it whichever way takes best advantage of the available air sources.

.bh.