Bottom Mount Radiators

[OC Maximus]

For those of you running double or triple bottom mounted radiators laying horizontally, which way does the air flow? Does the air come up from under the radiator and blow hot air on the GPU's or suck on the case and blow the hot air out of the case and on the desktop?

Thanks,

[ericFX1984]

well I set mine up on the bottom and cut the bottom of the case out, set the fans pulling air from outside the case to inside... the air coming out and into the case was 2c above room temp... so not hot by any far stretch of the imagination

it actually dropped the temp on my gtx260 quite a bit.

[OC Maximus]

Have any pictures?

[ericFX1984]

I might have some. I will have to check the backups on the server. I will see what I can find

[S3RV0]

In my old setup I had a 360 rad up top and a 240 rad on the bottom both as intake for positive pressure because I hate dust.

If you have you bottom rad as intake sucking fresh air from the outside, you might want to get some taller replacement feet as well.

[Polizei]

In my old setup I had a 360 rad up top and a 240 rad on the bottom both as intake for positive pressure because I hate dust.

If you have you bottom rad as intake sucking fresh air from the outside, you might want to get some taller replacement feet as well.

I never understood how positive pressure prevented dust. Don't you bring more air into the case (air carrying dust) when you set more fans to intake than exhaust?

[S3RV0]

http://www.demcifilter.com/positive_pressure.htm

and

http://www.silverstonetek.com/tech/wh_positive.php?area

[Philwong]

I never understood how positive pressure prevented dust. Don't you bring more air into the case (air carrying dust) when you set more fans to intake than exhaust?

I guess its easier to use dust filters on rad openings than sealing all the ventilation holes, gaps and etc.

Phil

[NaeKuh]

I never understood how positive pressure prevented dust. Don't you bring more air into the case (air carrying dust) when you set more fans to intake than exhaust?

dust doesnt get inside corners and other openings on the case because its being forced in postive pressure though the fan holes.

Vs.

Negative pressure, where every opening inside your case, even small cracks, can get caught with dust.

How realistic is it?
Meh... dust gets everywhere eventually, you cant fight it, it is one thing that will outlast even the mighty roach.
But if you think you can honestly seal your case up well enough to implement positive vs negative... then i think you have a U2 rack.

[Serpentarius]

dust doesnt get inside corners and other openings on the case because its being forced in postive pressure though the fan holes.

Vs.

Negative pressure, where every opening inside your case, even small cracks, can get caught with dust.

Polizei has point ... the more i think of it .. the more questions i get .. how much negative pressure are they? axial fans arent centrifugals, they cant generate enough pressure to create a semi-vacumn let alone vacumn to draw in the dust

it is possible to create a semi-vacumn state for packaging etc ... but to do so, requires a loud vacumn cleaner not just that, centrifugal motor

i've seen air leakage testing on homes where a large centrifugal motor is placed on the front door and the whole house (windows/doors) is shut tight. even with the differential air pressure, leakages doesnt have any dust around it

did we made a wrong assumption on the positive/negative pressure?

[GOZ]

Have any pictures?

This is old but, now I have a push/pull setup with the fans mounted outside the case, fans/case/rad/fans, and blowing into the case

[Church]

Polizei: in general:
Dust protection: dust filters on fans blowing in + positive pressure. (or dust filters on in-fans + any air pressure even negative one and air-tight case, to not suck up dust together with un-dust-filtered air from outside through holes in case/manufacturing gaps between details/gaps between 5.25 devices and mirriad of other small gaps any case has)
To get positive air pressure in simpliest way - to put more fans (if of similar performance) blowing in, then blowing out. You have to take into account drop of airflow when there are dust filters on fan, so it's not as simple as +1 fan blowing in. You can check resulting air pressure with something as simple as some smoke or flame of lighter if you put it at some fanless venthole of case .. to which direction it skews (or if smoke to where it gets blown off or sucked in)?
I wouldn't try to airtighten case. It's hard to achieve + might result in some uglyfication . Positive air pressure way simplier to achieve.