Question Regarding Airflow Setup

[ChthonicEidolon]

I'm running a HAF 932 case, and replaced the side 200mm fan with four 120mm fans for more airflow, and have had great temps.

However, there's only one exhaust fan I'm using, a single 140mm rear exhaust, but room for top fans (case top is mesh) and bottom fans (also mesh).

So, my question: if I placed even just one 120mm as exhaust on the bottom, would any of the airflow from the lower fans on the side of the case get a chance to hit the GPU/mobo? Or just be sucked right out?

With my temps, I don't really feel I need more exhaust (though it's important), but am thinking about putting one more 120mm on the bottom as exhaust, to help reduce dust and maybe a little ambient temp.

Heat rises, but in this case, all the heat is towards the bottom of my case and it's cooler towards the top, hence why I just leave the top as open mesh for heat to escape.

Just trying to figure out if it'd be worth it, or if it would just be an "air in the side, then straight out the bottom" scenario without getting a chance to hit any components.

Ah, the complexities of airflow...

Current temps:
E8600: 34C idle (approx), 41C load (approx) - Xigmatek S1283 w/120mm fan
ASUS Rampage Formula: 29/30C idle; 33/34C load
NB/SB: 36/37C idle; 39/41C load
GTX 280: 45C idle (fan @ 55%); 60-65C load (load temps vary w/ fan speed)

P.S.
An interesting thing... if I turn off one of my lower side fans, my mobo temp rises by 2C; if I turn off both lower side fans, my mobo temp jumps 6C(!), which I thought was nuts.

So, all the more reason I want to make sure the side intake is always hitting my mobo as much as possible.

 

[Elledan]

Heat rises. Exhaust fans go near the top.

 

[ChthonicEidolon]

Heat rises. Exhaust fans go near the top.

Heh heh, I know ...but as I said, in my situation the majority of the heat in my case is actually more towards the bottom. There's nothing but coolness towards the top of my case Perhaps due to GPU and SB/mobo heat.

So, if I'm going to add a fan to the bottom of the case, as I've said, I wanted to make sure it wouldn't just be sucking out any air pulled in from the lower side fans before it has a chance to hit my mobo.

Of course, once the aftermarket cooler for the GTX 280 is released, I'll have a 120mm blowing down and out the bottom of the case, so if airflow from the side fans can still get through that to my mobo, then perhaps a bottom exhaust fan wouldn't hurt...?

 

[nemesis27]

I see what your saying, with that huge fan I doubt it would suck it out, it would have to be greater than your 4 intakes, at the same time I don't know if you would benefit from it. I could see if you had a divider in your case and wanting to vent the lower chamber but ya don't. I personally, would exploit the heat rising theory and just use the side as you have, bottom too if you want, as intakes and run a top fan for exhaust, same with the rear.

You can always try it though for your own experiment If you do post back and tell us what you found out.

 

[ChthonicEidolon]

I see what your saying, with that huge fan I doubt it would suck it out, it would have to be greater than your 4 intakes, at the same time I don't know if you would benefit from it. I could see if you had a divider in your case and wanting to vent the lower chamber but ya don't. I personally, would exploit the heat rising theory and just use the side as you have, bottom too if you want, as intakes and run a top fan for exhaust, same with the rear.

You can always try it though for your own experiment If you do post back and tell us what you found out.

Glad ya get me

Yeah, I'm using four 120mm fans on the side, but wanted to exhaust out some of the heat from the bottom (and possibly some dust) w/o taking away from any of the side intake.

I do indeed think I'll experiment with it ...just figured I'd drop a line about the airflow first.

I was going to mount a 120mm fan on top, originally, until I actually switched to this case and realized that there is no warm air that can be felt at the top of my case (this case is huge!), instead, there's actually only cool air that can be felt from the top mesh. Of course, I'm sure there's warm air making it's way out, but the case is so big, that nothing can be felt out the top except cool air right now.

But, I can feel a bit of warmth in the bottom (and again, the dust) due to my hard drives, GPU and mobo SB. So, figured I might exhaust out the bottom. Probably wouldn't make a great difference though, I suppose.

You wouldn't want to intake through the bottom though, unless you want your system to become a vacuum cleaner, especially on a carpet, lol >.<

 

[Elledan]

Something tells me that ducting would be more efficient in this case

Laminar flow == good. Having lots of fans messing with the airflow inside the case == not so good.

 

[Zero82z]

Heh heh, I know ...but as I said, in my situation the majority of the heat in my case is actually more towards the bottom. There's nothing but coolness towards the top of my case Perhaps due to GPU and SB/mobo heat.

Putting exhaust fans in the top would still create an upward current which would draw up the hot air from the bottom of the case. It would definitely be a better solution than a bottom exhaust.

 

[ChthonicEidolon]

Putting exhaust fans in the top would still create an upward current which would draw up the hot air from the bottom of the case. It would definitely be a better solution than a bottom exhaust.

You're absolutely right, on both counts, though I wasn't sure if it would actually be enough to make any difference, due to there being mesh (with some wide holes, to boot) on the bottom of this case, which I've never had in any other case, plus the size of this monster.

As it turns out, slapping a 120mm fan on the top of the case, actually did make a bit of a difference. Bigger than I'd have thought, to be honest. Temps are as they were before (which is already good), but it seems that it occasionally drops or keeps some temps about 1C cooler, just from the one top fan.

Actually, both the NB/SB are almost steadily 1C cooler than they were, which for the SB, I find almost bizarre, considering where the temp sensor is (bottom-left, under my GPU; located it the other day).

As for the bottom... adding even one fan to the bottom of the case, actually did raise my mobo temp by 1-2C, so it indeed just sucked out some of the intake from at least one of the lower side fans.

So, while an interesting addition to this particular case, I'd definitely recommend not installing any bottom fans, and just leaving the open mesh for more warm air to escape. Don't use it as intake either, as it's just act as a vacuum cleaner, and the four side intake fans are plenty.

An interesting experiment.