Positive VS Negative

Hello.

Building a new system on some what of a low budget.. The case i have chosen for many reasons is the Antec 1100.
http://www.antec.com/Believe_it/product.php?id=NzA0NTA1&lan=us


The way i plan on setting up the air flow in the case is the front 4 fans intake, rear and top fan exhaust. My question is, what direction should the two fans on the window and the one behind the mobo be?

Thanks!

 

Davids layout is best.
The idea with cooling is to create a negative vortex that is to say that you pull just a little more air out of the case than you push in and with the CPU fan drawing air through the cooling element will provide adequate cooling for all but the most strenuous loads.

 

I'd push air in from the window to give extra fresh air to the CPU and vregs and forget about the one behind the mobo, I found it useless. Man, that thing is going to sound like an airport.:eek

 

From what I have read all of the above are correct lol, the negative flow suggested by David and Bill will give better cooling.
The positive flow suggested by Auggie will help reduce dust build up.
The theory on this is the positive flow forces dust out of the case but I think this really depends on how dusty your environment is.

I have an Antec 900 and have it set so the front 2 fans push air in while the back and top are exhaust and I currently have the window fan pushing in which is reducing dust build up, but I have a GTX480 on the way and may have to suffer the more frequent cleaning to increase the cooling power.
It's a little hit and miss since there are many variables.

But acording to the Antec 1100 Manual you should have them blowing inward.

I think I would probably have 1 in, 1 out and see what happens lol
Also remember the fans are variable speed so you can have them set up at different power/RPM's which again throws in another option.

 

although I'm pulling a weapons grade necro on this thread, it did come up in the top of a google search.

basically, I bought the eleven hundred a month or so ago, and I was curious about air flow, so I did my own experiment with the side fans after reading this thread, to see which fan config worked the best. my cpu cooler (hyper 212) is pulling air away from the gpu (7950/1.25v/1155/6000), and towards the 200mm top fan.

the results after letting unigine valley run for a few rounds on extremeHD:
- both side fans blowing in: core 68 | vrm 64/67
- both side fans blowing out: core 69 | vrm 68/71
- right side fan in, left side fan out: core 69 | vrm 65/68

I then ran the test again with both fans blowing in, and got identical results to the original first test.

my own conclusions are that
a) the top 200mm and back 120mm fan are likely pulling more air than 4 front fans and 2 side fans to begin with.
b) having my cpu cooler pull air up would fight with the side fans if they are pulling air out.
c) if I were to put an exhaust fan behind the motherboard, I might see more improvement than messing with side fans. I will update this post if I ever try it.

 

The issue here is not solely immediate temperature, but prolonged temperature due to dust build up, which can take months or longer, depending on your environment.

I trust and will build David GP's suggestion for a dusty environment. For a verified clean environment or if the user will clean his internals, say once in 4 months or so, I would pump air in with the sides. But lets's face it, most of us, are lazy, even those of us who know better; which makes David GP's build superior.

From a strictly thermal standpoint, with a clean machine, pumping air in from the sides will obviously give a lower temperature as cool air with a lower temperature is immediately servicing/cooling the important bits, whereas air in from the front and out the sides/back will have already cooled the hard disks and have risen a bit, so the lower temperatures will not be seen, as you have proven, but as I said, dust after prolonged use is of main importance here.

I also don't agree with dust going in to be blown back out, as there will be areas in your case with 'whirlpools' or eddy currents of air which will cause dust to accumulate there. Dust also gets stick or charged and attracts more dust.

 

You're absolutely correct about dust and heat. I've had the pleasure on more than one occasion of helping someone with their computer, only to find a beach on the bottom of the case, with sand bars on every component (2-3 times in more recent years that I can recall negative pressure setups... but obviously no air filters anywhere).

it is definitely on a case by case (pun intended) basis as to positive vs negative on the side fans. I tend to push my components, and generally keep my machine clean on a fairly regular basis for that very reason, so in my particular case (again with the puns), it makes sense to have intake on the sides, and for my particular setup; superior.

On another note though, 120mm fan filters are fairly inexpensive, but have not personally used them on the 1100 side fans so I cannot comment (I probably should buy some). as to aerodynamics and hot spots, the eleven hundred shouldn't have any near components (besides the optical bays) if cable management is good.

but yeah, if someone is lazy, and lives in a dusty environment, and runs everything at stock, Its probably better with side exhaust, so long as there is an exhaust fan behind the motherboard, or that fan spot is sealed, so as to not pull dust toward the back of the motherboard and into the case, due to the large cut-out behind the mobo.

 

Hi

Interesting thread, I once worked with an older guy that claimed he used his wife's old stockings, over the intake fan, to prevent dust getting sucked in.

I was like :-o