Bottom PSU install?

Borsch · 11 Jan 2012 at 17:32

Hello,

I am about to attempt my first PC build and I have ordered PC Tower case (Casecom 7688) that has PSU slot at the bottom. My current PC tower has PSU at the top, with PSU's large fan facing down (I am not sure if it sucks air form the case or into the case).

If I was to fit my PSU (Thermaltake Tough Power 500 btw) with the large fan pointing down, that allignment would not make sense? THe large PSU fan has to face the case innards, not the case floor? But the case bottom plate does have vents - confusingly enough :confused:

Which way do bottom fitted PSUs face - fan up, or fan down?

CHEERS

stulid · 11 Jan 2012 at 17:53

If there are vents in the bottom of your case for the PSU to suck air from, then place the PSU with the fan facing down.

So it draws cool air from under the case and then through the PSU body and out the back.

If your case is sitting on top of carpet? then you will want to have the PSU fan facing up.

So it draws air from within the PC and exhausts it out the rear.

Tealc · 11 Jan 2012 at 18:16

There's no right and wrong way of mounting PSUs in the foot of cases if the case has both options available. I went with upwards because there was only about 1.5cm clearance so there'd be additional noise from turbulence. Flipping it allows me more clearance but shortens the available cable lengths to components by the length of the PSU.

Borsch · 11 Jan 2012 at 19:23

SO do PSUs exhaust from the rear of the case? As opposed to suck it from the back and vent over the innards? Are they all the same in that regard? Sorry for noob questions

So it draws air from within the PC and exhausts it out the rear.

I went with upwards because there was only about 1.5cm clearance so there'd be additional noise from turbulence

(aren't these quotes contradictory?)

I think all cases have about 1.5cm clearance between their base plate and the floor (mine is laminate, not carpet btw).

Ideally I would like my PSU to draw in cold air from outside (through its backplate opening) to the inside of the case (via its large fan). Then this air would warm up through contact with GPU et al and naturally rise to the top of the case where it would be sucked out by fans at the top. For bottom placed PSU to suck air out - does not make sense as air at the bottom of the case is cold anyway.

Still confused :confused:

Louis_Y · 12 Jan 2012 at 00:54

PSUs usually drawn air in from the large fan and exhaust it out the back. If you have vents with filters in the bottom of your case, I'd mount it with the fan facing down. The air flow is to keep the PSU cool and should have little effect on your case temps.

In your scenario, cool air would be drawn in from the back, heated up as it passed through the PSU then vented into your case, possibly increasing case temps (and GPU temps etc.).

stulid · 12 Jan 2012 at 04:01

Borsch said:
I think all cases have about 1.5cm clearance between their base plate and the floor (mine is laminate, not carpet btw).

Ideally I would like my PSU to draw in cold air from outside (through its backplate opening) to the inside of the case (via its large fan). Then this air would warm up through contact with GPU et al and naturally rise to the top of the case where it would be sucked out by fans at the top. For bottom placed PSU to suck air out - does not make sense as air at the bottom of the case is cold anyway.

Still confused

In your situation have the PSU mounted with the fan facing down.

Borsch · 12 Jan 2012 at 09:24

stulid said:
In your situation have the PSU mounted with the fan facing down.

Thanks, I will follow your advice.

Would you recommend raising the case from the floor to to allow more air get to the PSU fan and keep it further away from floor surface dust? And would be the best way to do that - buy longer legs for the case?

stulid · 12 Jan 2012 at 09:47

You dont need to do that, just keep the floor clean around the case and you'll be fine.

Borsch · 21 Jan 2012 at 21:55

Just thought I'd update this thread with a couple of poor quality pics

This was my first built PC and I am thrilled with it.

I ended up going with advice of Stulid - put my PSU with fan facing down. I think this way it should be more protected from dust as if it was facing up, dust would fall into it due to mavity AND due to its fan suction effect.

I'm very happy with Casecom 6788 case - cable management, no sharp edges, black interior for better heat absorption/radiation, screwless bays (which actually do work very well), ventilation vents in the top of the case which help with negative pressure. The front fan was initially very noisy with bearings ticking, but after a few days (which I spent researching its replacement) it worked itself in and now it is about as quiet as my other Xilence Red wing fan. Did I mention its £22?

Thanks for your help!