New direction for case air flow
Got this idea from reading about the new BTX standard. I am thinking about reversing the flow of the front and rear case fans. The thinking is that cooler air is being blown on the CPU. The downside... hard drives are not getting cool external air. To solve the problem I thought about adding a 120mm fan over the drives.
Want your comments and thoughts on how to improve the set-up.
First is the current fan set-up (I'll post a reply for the second pic):
Any comments or thoughts
The proposed air flow:
Snafu, I did a lot of testing in this area based on theories and test results done by Thugsrook and others. As far as fan holes, I have almost exactly the same setup. Keep this in mind when designing your case cooling: More isn't always better, and a lot of times it's worse. The whole purpose is to get fresh air into the case and over the components you want it to, then back out of the case as quickly as possible.
My findings for the perfect (and quiet) airflow:
A 120mm blowhole fan.
A hole in the side directly opposite the CPU with a filter--no fan.
A hole in the side, below the first one with a filtered fan blowing on the video card and lower half of the mobo.
A 80-92mm exhaust fan at the rear of the case.
This is a negative pressure setup that is near silent (depending on your choice of fans). Please note that ANY additional intake fans raised the case temp. Also note that I have no cables or wires obstructing airflow. Air gets pulled in over the mobo and cpu and immediately get's drawn out the back or out the top (or into the PSU). Pay attention to what's going on inside your case, if you have monster fans blowing on the CPU and memory it could be causing a mess in there which could be causing more harm than good. Remember, you want the fresh air in, but you also want to get the hot air out ASAP. This isn't amount the volume of air, it's about airflow...the better the airflow the cooler your case will be. At the end of the day you'll have to do some of your own experiments if you want it to be perfect.
Note about drives: The air that gets pulled in below the video card has to go around the card and right by the drives on it's way up to the blowhole. This should be sufficient. I've never had fans blowing on my drives and have touched them right after heavy use such as video encoding or burning and they were at worst lukewarm to the touch. I wouldn't waste your time with that unless your case is funkily designed or your computer is constantly using them heavily....you may end up disturbing the flow.
Like I said, this is all based on test results, but this is what worked for me, my case and the particular fans I chose. You may have to tweak this a bit differently to make it perfect....
snafu, that set up will drop your cpu temp, that i'm pretty sure of. i'd say give it a try and see what happens but i'm not sure you'd need the extra 120mm by the hds
thinking of this makes me wonder about my set up.
here is my set up. i got a equal amount of fans blowing in and out.
2x80mm are blowing in, plus the 120mm in the front on the hds
1x92 on the back of the case blowing out and 2x120 (one in the psu) blow out as well.
not sure if the set up is the best currently. anybody got any opinions, ideas or comments
Also part of the equation I think is where your CPU HSF delivers the air on exit. A stock Intel HSF exits the air horizontally and the MCX4000 I used to use distributed it evenly 360 degrees. The SP94 which is definately the best of the bunch delivers the air vertically. Half mostly goes into the PSU but the other half gets dumped on the video card. If you're overclocking a Prescott and the video card at the same time things can get warm real fast on graphic intensive stuff.
note to anyone using a blowhole exaust:
baffle off the PSU (the open grilled side) for better results. otherwise the blowhole may actually pull in air thru your PSU.
Thanks for the tips. Sounds like I need to run some tests and write it up (too bad I'm not much of a writer).
I did leave somethings out. All fans are 80mm that came with the Thermaltake case. All intakes have filters. All fans are controlled.
I have a stock Intel heat sink but have a Zalman 7000-AlCu coming soon (should blow out in 360) along with an Artic Ice video cooler, a 120mm fan for the hdds and two 50mm fans for the ram (need to jury rig something). I went nuts one day on a site and ordered a bunch of stuff.
I agree that even uninterupted air flow is the best - get it in a get it out as quickly as possible. Side fans and blow holes can disturb the cross-case flow and should be used with some caution. My main goal is to try and reverse the air flow to deliver cooler air to the proc without killing the drives (2-Raptors). I think the concept sounds okay on paper but the proof is in the pudding.
I have to get started on some wire management and alter the guts of my rig a bit to get a cleaner air flow (should take pictures before and after to see if I can get a good house keeping award). Right now I have only cleaned up a little but it is still looking messy.
What material is used to baffle the PSU and how far down is it run? Any links to a thread or post on "how to" for this? I am interested also in using ducting/baffles to direct the air flow but not sure what would be good material to work with.
thin cardboard and clear packing tape.Originally Posted by Snafu
most PSUs have 2 fans and an open grill on the front side near your blowhole ~ block off that open grill.
Thugsrook - thanks for the tip.
My psu is exactly as you describe. Not sure why they put the vents on the side. Would be better if they either added a third fan or not even have the vent. It would be even better if they put the second fan at the top of the case and blocked off all the inside vents - the psu woudl not draw any air from inside the case. Maybe I should try to turn mine upside down and cut a hole on the top
. If only I had an older case to hack up.
a good leason i've learned is that no matter how good a case's air cooling is, its only going to get as cool the air going into the case. location of the case can matter as much as the air flow in it.
because of that, i want winter to come back. 16c case temps when its next to a open window. the only draw back was i had to wear a hat and gloves to keep from freezing.
To answer why the are holes on the back of the PSU is because not every case has a blow hole, so because of those holes on the PSU plus its fans blowing out this gets rid of the hot air that a blow hole fan would usually take out. And the way I have my memory cooling is that I have 2 40mm fans on the side top and bottom fo the memory blowing upward which blows air up the sides then the blowhole gets rid of that rising out air.
Last edited by Android Vageta; 07-04-2004 at 11:58 AM.
KM - yeah room temp plays a good part too. I'm lucky in that my play area is in the basement with room temps never going above 18C (~65F) even when it is >30 outside. I am also lucky to have AC to help cool thing down if it gets too hot. Could always try to run a vent down to the case
AV - thanks for the news. I was thinking about the same fan set up on the ram but not too sure how to rig them up. How did you rig this up? My video card is about 3/4" under dimm#1 so it looks a bit tight just under dimm#1. It woudl be interesting to try and build a shrough/tunnel over the ram with the two fans to keep the air only over the ram and not interupt the air already flowing through the case. It's all good in theory but I need to figure out which material to use before this can happen.
Cheers, buds.
what Mikki explained earlier....
(the thick line is the PSU baffle)
Last edited by ThugsRook; 01-05-2005 at 05:19 PM.
i'd give negative air flow a try. i just switched my rig to have all but 2 fans blowing out. temps dropped about 2-3c for the system temp. cpu temp only dropped a good 1-2c
Thanks
I am going to try negative and positive pressures and see if there is a difference. No elaborate testing just running F@H and/or Prime95 and watch the temps. I will also test the effect side fans, blow hole and baffling off the PSU. I will do this before reversing the fornt/back case fans.
Just received an Arctic Ice video cooler (rev.3 for my 9600XT) and the fans (120mm and 2-50mm). I am sure the video cooler will help with the case temps. Just waiting for the Zalman HS to arrive.
I have a bunch of testing to do but will post what happens.
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