two case fans on the back

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ImportPsycho

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Jun 22, 2003

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Vancouver Canada

• Jul 26, 2003

• #1

does anyone have this setup?
two rear case fans, one intake, one exhaust?
or both of them intake?

since rear case fans are like right next to cpu cooler, wouldn't be better to intake?

 

John LA

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Jan 31, 2003

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Bloomfield, CT

• Jul 26, 2003

• #2

I have 2 rear case fans which are both exhaust. My intakes are 2 front mounted fans and 1 side mounted fan. The problem with using a rear as an intake is that it can pull in warm air that is being discharged by the PSU. The side intake helps to provide cooler air for the CPU and vidoe card.

LA

 

stan03

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Mar 30, 2003

• Jul 26, 2003

• #3

I have both set as exhaust, but you could try reversing them and set the front as exhaust and see what gives you better temps

 

Ugmore Baggage

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Feb 12, 2002

• Jul 26, 2003

• #4

the problem with intakes in the rear is becasue they are so close to the PSU exhaust, and PSU fans are not usually strong, you wind up sucking a lot of hot air. that air heat up inside and spews out, which gets sucked back in... and that sucks and blows at the same time.

creativity in fan positioning is great, but try not to forget the ones you can't change.

 

Ciffer

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May 24, 2003

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southeast MN

• Jul 26, 2003

• #5

that makes no sense to me, i have 8 fans, 3 in rear(including psu fan) all exaust, two on side near the rear both intake, 1 on top exaust and 2 in front both intake i see no reason you'd have 2 right next to each other in opposite directions, if i were i'd set both at exaust

 

Weltall

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Jun 24, 2001

• Jul 27, 2003

• #6

plus dont you want to follow the general rule that heat rises which would mean try to keep you intake fans a tad lower than the exhaust fans? I have to Intakes on the side of my case, 1 exahaust in the back by which is slightly higher than the higher intake fan and two smaller exhaust fans near the top. It seems like a good setup that will keep cold air moving in and hot air out.

 

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icantgetanyname

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Jun 13, 2003

• Jul 27, 2003

• #7

what about this.
i have the lower rear fan as intake.
the reason is it is a few inches from the smartfan2
on my hs. this way it gives fresh air right above the
hs fan. otherwise it would be taking air away from it right ?

i notice 1-2* lower this way from having both exhaust.

 

stan03

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Mar 30, 2003

• Jul 27, 2003

• #8

really? im going to try that, i would think that since the two fans would be fighting each other, there would end up being a raise in temps.

 

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chipsdeluxe

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Jul 7, 2003

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Austin, TX

• Jul 27, 2003

• #9

Check out this AMD Cooling Guide.

From what I understand, the proper airflow in a system is: cold air into the case from the bottom-front and side. Warm air out of the case from the back-top. Reasoning behind it is that Warm air rises, and you have a constant stream of cold air flowing across the cpu hsf. That is also why many psu's have large fans on the bottom, to pull air across the cpu better.

Of course if you're getting better temps with one of your rear fans as intake, then throw all that theory out the window and go with what works!

 

q149

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Nov 10, 2002

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Japan

• Jul 27, 2003

• #10

I have the 2 rear as intake... I have the psu exhaust being deflected upwards so it's not sucked back in there. Doing this with these fans dropped my temps drastically. You might want to have a blowhole though.

 

S

slyy

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Mar 1, 2003

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Dallas, Texas

• Jul 27, 2003

• #11

Don't forget the fact that your PC is probably about < Foot from a wall or corner. This means that all the heat that the PSU puts out will stay along those walls (it has no where else to go). Basicly, I wouldn't want to try and cool my unit with the same warm and muggy air my PSU just kicked out. The only one who can truly judge this situation is you! Try various setups and monitor each under *various loads* not just idle, then see which works best and that's your final answer!

Good luck

 

q149

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Nov 10, 2002

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• Jul 27, 2003

• #12

That's why you deflect the psu exhaust upwards.. then it dosen't drop back down to the intakes cause it rises.

 

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icantgetanyname

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Jun 13, 2003

• Jul 27, 2003

• #13

its also gonna depend on the size of ur case.
i have a very tall one ... so the lower back fan is about 1/2
way up the case.

and it the fan is VERY close to the hsf ... seems like having no fan would be better than having one pull air AWAY from the hsf

 

C

chipsdeluxe

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• Jul 28, 2003

• #14

icantgetanyname said:

seems like having no fan would be better than having one pull air AWAY from the hsf

Click to expand...

It's all about creating a flow of air across the hsf. Having a fan near the hsf that blows out of the case won't create a vacuum over the hsf; instead the fan will draw air across it. If you have a fan in the front blowing air into the case, and one in the back blowing air into the case, the two streams of air will collide in the middle and flow will be reduced. It is the same reason that it is a good idea to keep cables out of the way and use rounded cables when possible. They don't impede the flow of air.

Of course, every case is different and it is impossible to predict the exact flow of air, so individual results can show better temps with all different kinds of fan setups. I think the best thing to do is try the fans in all different directions and positions, and see what produces the best temperature.