Mounting question for bottom cases

[you2]

Ok. This is a really stupid quesiton (I think). I have a seasonic 760 psu and I'm mounting it in a bottom mounted case. The instructions sez:

"Depending on the type of case, correct mounting of the power supply will result with the fan side top cover facing mainboard. This does not apply to all types of cases."

Can instructions be more ambiguous ?

I presume the text on the psu should face up so the fan will face down on a bottom mounted case; but what I thought was obvious before has sometime not been so; so is this correct ?

 

[tomoyo]

If you're bottom mounting, you probably want the fan facing up so there's a place to draw air in from. Basically whatever source of air you have is where you want the fan facing.

 

[alaricljs]

And some bottom mount cases provide airflow at the bottom, so the mounting orientation would remain the same as a top mount case. This is the way Antec's P18x series of cases do bottom mounting.

 

[you2]

So sometimes the fan should face up but other times it should face down; arrrggggg so which is correct ?

In this specific case the PSU is about 1/4 of an inch off the bottom (there are two rails that hold it off the bottom of the case; and just below the fan there is a filter which (to me) suggest it is intended to draw air through the filter hence down facing fan; but perhaps I'm totally miss understanding the layout (hence the original question). Maybe it is to allow for better ventilation and the fan shoudl be facing up so it can draw air away from the video card ?

And some bottom mount cases provide airflow at the bottom, so the mounting orientation would remain the same as a top mount case. This is the way Antec's P18x series of cases do bottom mounting.

 

[alaricljs]

Truly it's up to you, but in my opinion that filter would suggest that you have the PSU fan facing down. PSU fans don't kick in strong until the thing gets quite warm, so that heat doesn't escape into your video card you might want to have the fan facing down. You can always try it both ways and make an empirical decision if you think it's worth the hassle.

 

[dawp]

In a lot of cases there is only one way to mount the PSU, it depends on the screw holes.

the way I read that is the preferred method of mounting is with the fan up in bottom mount cases unless your case wont allow that.

 

[you2]

But isn't the fan intake with the out take is always from the case (where the power switch is located) ?? If this is true then when the fan runs it will pull hot air away from the video card (maybe not a good thing for the PSU ?)

Truly it's up to you, but in my opinion that filter would suggest that you have the PSU fan facing down. PSU fans don't kick in strong until the thing gets quite warm, so that heat doesn't escape into your video card you might want to have the fan facing down. You can always try it both ways and make an empirical decision if you think it's worth the hassle.

 

[alaricljs]

But isn't the fan intake with the out take is always from the case (where the power switch is located) ?? If this is true then when the fan runs it will pull hot air away from the video card (maybe not a good thing for the PSU ?)

Yeah if you have the fan pointed up, when the fan runs it'll suck air away from the video card. It depends on your particular PSU tho. Mine does nearly nothing to pull air out of the case even when my cpu/gpu are fully loaded. For me it's best to have the fan intake down so I lessen the amount of heat rising out of the PSU and into my GPU. Then again I have a P180, so the PSU is in it's own isolated (somewhat) area at the bottom and has a case fan pushing air through it (set to low speed).

 

[BoomerD]

While you MAY be able to mount the PSU with the fan pointing up, I wouldn't do it that way unless heat build up is already a problem...and if that's the case, you need to look at better thermal management anyway.
Mounting the fan so that it points up leaves you exposed to having a screw come loose and fall into the PSU...NOT a good thing.
Besides, the PSU should run cooler if it's drawing air from outside the case...and the cooler a power supply is, the more efficient it is.

 

[infoiltrator]

In the day of 60-70 % efficient power supplies (most of which lower watt than today) the fan played a part in cooling the case. White Papers on the Pentium 4 describe this.
A modern case, certainly one with bottom mount should have fans sufficient near motherboard. Usually a top and back.
80+ power supplies, in pursuit of efficiency try not to run fans.
Some cases Do ALLOW up or down mounting, your choice.
If you fear dropping things into the fan in an up orientation, a filter pad works well enough, lol
Personally, the idea of the psu drawing cooler air thru a filter appeals to me.