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PSU fan facing down or up?

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June 19, 2009 2:14:49 PM

Hey everyone i was looking at some system mods and noticed that some people put their power supply in the case so that the fan was facing up near the mobo, i guess to act like an exhaust and it got me thinking;

I am new to pc building and when i got my power supply i mounted it so the fan was at the bottom because there were vent holes and my manual told me too lol.

but i just wondered what provides better airflow? and if i should flip my power supply?

and i thought if the PSU was sucking in hot air from all the other components wouldn't it shorten the PSU's life span?

I have a CM 690 case and just wondered what is best?

thanks in advance

More about : psu fan facing

a c 144 ) Power supply
June 19, 2009 2:27:18 PM

I have Antec 900 cases, also with the bottom mount PSU. I mount my PSU's with the fan facing upward toward the motherboard.

Except for hard drives, there are really no heat producing components in the bottom of the case. The video card and the CPU are mounted higher. In my system, PSU exhaust air is about 3 C. above ambient. Of course, it helps that I tend to operate my PSU's at around 50% - 60% of capacity.
June 19, 2009 2:27:29 PM

HI,
I do the same in my tj-09, this way the psu never take pre-heated air from inside the case.
I think it's better. Just be sure you have a dust filter , because if you take air from the room to get the psu in low temp and this air is full of ... It's not a better think too do in long term. If your case don't have dust filter some pc mod shop sell kit to stick on the pc or you can make your with velcro.
bye
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June 19, 2009 2:33:44 PM

thanks for the advice, well the problem was that i had a faulty psu so i rma's it but decided to get a different module (650w be quiet!) and its great but maybe a little too tight in my case, i bought two ac ryan filters, one for an additional fan at the bottom of my case and one to place under my psu but it was too tight and couldnt crew my psu securely. and obviously i dont want a dusty psu so i think i might flip it. cause i cant be bothered modding it, a bit OCD like that lol.

aswell to jsc i doubt that i even use all the juice in my psu its 650w but i think i couldv'e gotten away with 550 or even 500w but i just wanted it to be a bit more future proof.

the size of the cm 690 would there be any problems with mounting the psu fan facing up towards the mobo?
June 19, 2009 2:35:24 PM

btw i have wooden floors and dogs, and everytime i tidy the room an hour later it is full of dust...
a b ) Power supply
June 19, 2009 4:13:19 PM

burrellbuzzman said:
and i thought if the PSU was sucking in hot air from all the other components wouldn't it shorten the PSU's life span?


And put ice cubes on incandescent bulbs to prolong their life.

Temperatures are ideal for electronics even if it is too warm to handle. Electronics only get too hot when you touch it and leave skin. This is an argument over trivial single digit degrees when destructive temperatures must exceed hundreds.

Airflow direction does not matter. Just as long as all fans are contributing in the same direction. Just as long as airflow is not restricted by a ribbon cable. Airflow that is more than sufficient means your hand cannot even feel it. One fan in the power supply is more than sufficient airflow for most every computer. A second fan means if the first fan fails, the second fan maintains airflow. Or so that second fan blows air in a hotspot created by a misplaced ribbon cable.

Moving too much air only makes things worse; causing dust problems.

Too many worry only about what they understand. They understand heat; so hype it into an evil equivalent to Saddam. Don't worry about direction or the amount of air. Just make sure air is continuously flowing in one direction - as so slowly that no human hand can detect that airflow. Air moving that slowly is massive cooling.
June 19, 2009 9:26:33 PM

Glad to hear someone with some oldschool computer sense.

I'm guessing you don't believe in the cooling power of blue LED fans do you? each LED actually absorbs 1degree of heat hahaa

computers are beginning to get of similar to the auto trends of kids putting stickers and spoilers on honda civics and thinking they have a racecar.

I actually agree somewhat with westom, but i'll gladly keep my CPU, GPU, and PSU fans those chips do get into the hundreds without a good heatsink or fan setup. If you want to prove what hes saying crack open a HTPC or a dell or some manufactured PC they achieve cooling just fine with only a couple quiet fans
June 20, 2009 1:01:39 AM

HEY i have just read your comments and have just come in from a night out, i hope you are in the UK only so you have some idea as too HALFWIT (AKA freddie staying in the BigBrother house lol)... I must be drunk too care who is evicted lol... i am too drunk to make full sense of westoms point but i think it kinda hits home a little with the help of franchise's comment too...

at the moment i have just put the PSU upside down (or maybe the right way up depending on what you think is correct? (fan facing mobo-my room is too dusty to have it facing down-i HAVE DECIDED))

I think westom is correct everyone make this big issue of heat and yeah ok it matters if it is absurdly high but if it is always around the same then no worries???

i have a gigabyte mobo i think i said the model above, and EasyTune6 says my CPU is at around between 35-39C and the system is about 38-41C and the default warning limits suggest too me that the whole thing is over heating but but 1C

so you know i dont see the problem anymore again thanks for the help and please do still comment because i value everyones opinion; including jsc, westom and franchise hope too hear from you for some more advice.

thanks rob
June 20, 2009 1:05:40 AM

East Tune 6

System; 41C
CPU; 34C

System has just gone up 1C to 42C what the F***? i have no idea what is "correct" lol hope everyone has had a good fri night and weekend
a b ) Power supply
June 20, 2009 1:12:44 AM

Which way?

Mount the PSU so the fan is directly outside if possible. Why pull the case hot air through the PSU?

Most gaming PC's should have at least the following fans:

1. CPU fan (preferably 120mm with a large heatsink)
2. 120mm case fan (can be low flow)
3. PSU fan (internal)
4. graphics card fan (preferably blow air out the rear of the case)

optional: for older, hotter hard drives a really low flow fan to blow air across them mounted at the front; it also sucks in a little air for air flow through case
June 20, 2009 1:25:35 AM

well before i went out tonight i decided to mount the psu so the fan was sucking in air from the case and exhausting it out, i can change it back but the fan isn't directly under the vent holes in my case when i mount it facing down so the fan is sucking in "fresh" air...

jsc has a slightly taller case than mine by a couple of centimeters so i dont see the problem mounting it so the fan is facing the mobo? and seen someone mount their psu facing the mobo and their case was slightly smaller in height than mine,

i have a xigmatek cpu cooler with 120mm fan and my GPU is a XFX4830 hopefully switching it soon for a 4870 or 4890, so they have their own cooler which exausts air from out of the case?
January 23, 2011 8:27:28 AM

I realize this is an old thread but I just found it a few minutes ago. I am mounting my psu fan facing up towards the cpu. The letters on the psu case will be rightside up facing the person opening the case. I realize this has no affect on cooling but it seems like that was the designers intent, that is, not to be looking at his finished new design with the labels upside down and then to be content with his work. I was planning when it is completed before I anchor all the wiring down for good, to check the flow of air and to make certain it generally starts at one side or corner of the case and exits the opposite side or corner. I appreciate all the comments on every site, I learn from each one.
a b ) Power supply
January 23, 2011 7:50:48 PM

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