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Here's an experiment I'm going to try...

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rugby

King of Cats Senior
Joined
Feb 2, 2001
Location
Chicago, IL
...I saw this idea mentioned in another thread, and already had the parts on order. Right now I have an Alpha Pal 6035 with a Sunon 60mm fan on it. On the left side of the case there's a 120mm Sunon fan blowing air in. I just got a 430w Enermax hoping it would suck more air out and hopefully even out the airflow, but unfortunately it hasn't. I just cannot get even airflow with this case due to it's crappy design. I have an 80mm fan in the front bottom and a 60mm one on the back(due to the bevel in the case). Here's the idea we were toying with:

I'll take an 80mm->60mm fan adapter for the Pal and put an 80mm fan set to suck. I've got the 120mm fan right above it (on the side) set to suck also. I'll put another hole on the side to suck air in (the bottom front fan can't do a whole lot due to the front shell). Now, the 60mm fan on the back will be set to suck air in for the purpose of evening out the airflow.

Does this sound like a good idea? Am I missing anything?

Thanks.
 

SickBoy

Inactive Moderator
Joined
Jan 13, 2001
Location
Minneapolis, MN
sounds like you're doing all sucking and no blowing... he he.... I've heard that the sucking/blowing needs to be even for pressure purposes.... anyone know more about this?

SickBoy

P.S. I would try some different combos and see which works the best.
 

klosters64a

Senior Member
Joined
Dec 17, 2000
Location
Seattle, Wa
The idea is to balance intake and exhaust volume. Conventional wisdom is that a little overpressure(more intake volume than exhaust volume) is a good thing. Overpressure helps keep your case's interior from being a dust magnet from hell. This is the theory, at any rate.

If I read your post correctly your present intake and exhaust(assigning "average" cfm ratings to your fans) sitch yields ~60 cfm overpressure. This is more than a little. Too much overpressure is said to have a bad effect on the efficiency of CPU fans.

The "magic" bullet is to cut a blowhole for a 51 cfm 92mm Sunon fan into the top of your case. Blowholes on the tops of cases aren't the best way to go. A 92mm exhaust fan positioned in the upper rear of the case is better. The top mounted blowhole "steals" some of the airflow that's better put to use passing through your PS. At least this is true with my mid-tower.

If your case has a mount point for a 60mm fan in the upper rear of the case(which is better than none)it's quite possible that the top of the case isn't removable. At least not easily!

The best way to prep a case for OCing is when it's brand new and empty. Steel fragments and powder are harmless when removed before the mainboard goes into it. Cutting away the cutesy fan grilles, or creating mount points for serious fannage is a boon to ventilation. If you're lucky, no panel cutting is necessary!
 
OP
rugby

rugby

King of Cats Senior
Joined
Feb 2, 2001
Location
Chicago, IL
Thanks for the advice! Yeah, the top of the case is actually riveted onto the frame, so taking it off is going to border on silly. My PSU has monster length cables, which are shoved into the bay beneath the cd-rom. This basically blocks airflow anywhere above the PSU, so putting a blowhole on top would be kinda pointless.

I did sort of get my sucks and blows confused. Thanks for pointing that out. The pressure inside is a LOT higher than the pressure outside because I'm sucking a ton of air in right now and now blowing out a whole lot. That's why I was thinking of making the 120mm fan blow out and have an 80mm and 60mm suck in.

I wonder if anybody's overclocked using a desktop case. VEntilation would be a snap, just a big 150mm fan right over the heatsink blowing out and a couple of 80mm's on either side sucking in.
 

Hoot

Inactive Moderator
Joined
Feb 13, 2001
Location
Twin Cities
One of Hoots banal points

Actually, more pressurized air cools more efficiently than less pressurized air, because it is more dense. Just like water cools better than air because it is more dense. However, denser air makes the fan pushing it work harder and axial fans are not very strong, until you get into the high priced units.

Hoot