SOLVED I need expert cooling advice

[bURN]

Hi, I am not trying to overclock my computer. But I am running a high-end, custom-built machine for use in my recording studio. I am having trouble with it reaching really high temps inside the case (over 100 deg.). I'm not sure what the processor is running at. I've got the computer in an isolated case that I built to reduce noise, because the machine is in the control room and needs to be quiet.

I'm running a PIII 800
3 IBM 10,000 rpm Ultra160 SCSI hard-drives
several other Jaz, tape back-up, CD-RW, etc.
Matrox G450 dual video
And many other sound cards, modems, etc.

It is mounted in an Appro brand Server-type rackmount chassis. It has 3 very noisy fans mounted in the middle of the chassis that pull air in from the front across all the drive bays and blow it out the back across the motherboard. The power supply,of course, has a fan. And the CPU is a slot 1 type that I got from STEP Thermodynamics with 2 fans mounted on it.

The rack enclosure that I built to house the chassis and keep down noise is big. It's made from 3/4" ply. Fully enclosed, with the chassis basically floating in the middle of it with a few inches of space for air flow all around it. In the back of this box are two quiet fans. One is blowing air in on the bottom, while one is blowing air out at the top. They're sort of creating a loop of air that comes in and blows under the chassis to the front, up, and back out over the top (hopefully the internal chassis fans suck the new air in and through when it gets to the front). I've got about 3" between the rack-case and the wall, to allow air to get in and out of the fans.

I thought this would all be enough ventilation for the computer to be happy, but it quickly heats up to about 102 degrees within about one half hour after turning it on. And this computer I usually leave on 24/7. I have been having really bad video signal problems when it gets hot, and I need to make sure that this computer is performing at optimum level, it is what my business is centered around for recording.


****Does anybody have any ideas as to why this is not ventialting properly or any other ideas I might try in order to bring down the temp on this beast???
I know I can always take off the front and back lids of the rack-mount, but then the noise problems return--and that is what I've been trying to get rid of......


I would appreciate any feedback!!!
Thanks,

Chris
pSYONIC Laboratories

 

[klosters64a]

In theory, ducting cool air into the bottom of your noise isolation "chamber" and then hot air out of the top seems to be the solution. Easier said than done! Physically large, high capacity fans that are outside of the room seem the ticket. They gotta move some cfm, but rotate slowly while they work. Please, keep us posted!

 

[LimeyGreg]

Firstly, what is the cfm of your quiet fans? Also, just because you have two fans running doesn't mean you are doubling the air flow. It looks like your case fans don't have enough cool air to work with and will just re-circulate the air inside the wooden case.

I'd suggest adding two more quiet fans, one at the bottom, the other at the top. Disable the three rack fans (they are generating unwanted heat and noise), remove the top and bottom covers of the server and then put foam baffles around the server - between it and the outer case. The theory is you will now force the air being pushed in from the bottom up through the computer and out of the case at the top.

I think in your present set up that the air is just passing around your server case and is not really helping much.

 

[bURN]

Thanks for the ideas, guys. The two fans that I have installed on the outer rack unit that I built are only 21 cfm. I know that they are pretty low flow, but they also only generate 21 dB of noise, which is what I really want to avoid.

I figured that with one fan blowing in air on the bottom and one blowing out on the top, that this would be enough. Is it possible that the air is just not circulating around the computer enough, maybe just coming in to the outer rack and going right back out?

Would it help to maybe turn the other fan around, so that they are both blowing out? I really appreciate your feedback!

Chris

 

[bURN]

Hi, me again....
I did some air routing in the outer box to assure that the air goes in under the computer case and gets to the front where the computer fans will suck it in. This has helped some. It brought the ambient temp down from about 102 to about 96. It's working better now.

*** Any more suggestions? I can't really take off the lid of the computer case and the bottom is fixed, can't be removed, so those ideas may not work.

*** What is the highest temperature that I should be operating at for good performance?

Thanks again....
Chris

 

[Fink]

I would suggest that you replace the box fans with 120 mm units, the lower CFM ones, and run them at 5V not the normal 12V. That would give you more flow volume without compromising the noise too much. Adding more fans at the lower voltage is another option. It looks like you have an airflow problem within the box, as rack mount cases then to be very well ventalated. Also overlooked is the position of the intake and exausts. Make sure that you have a clear route between the box intake to the case intake to the case exaust to the box exaust. AT the very least have cold air blowing in the bottom and hot air out the top, no sense in fighting convection.

Make sure that you are not recirculating hot air that you are exausting out of the box back into the box itself through. A bit of carboard ducting will allow you to direct hot exaust up and away from the intake fan(s).

Colder air also tends to pool at the bottom of the room, so get the intake as close as possible to the floor. Ducting also works well for this.

If you are having a problem with noise, make sure that you case fans are mounted on rubber or silicone grommets as a lot of the noise comes from fan vibration resonating throught the case.

I recommed that you have a look at www.7volts.com for some ideas and good discussions about noise reductions.

Cheers!