Cooling multiple GPU's

I have been running as many as 5 GPU's. 2 Geforce GT 240's, 2 EVGA GT 240's and a Zotac GT 220 at the same time on a MSI 890FXA-GD70 m/b, with a 2.8GHz AMD Phenom II X4 820, 2G ram, a DVD drive and a Corsair GS700 power supply in a mid sized generic tower case for about 6 months now. This runs at 1.1+ TFLOPS or 5.9+ TFLOPS+ per kilowatt for those with a power budget. My CPU temperatures are 50 to 53 degrees C and GPU temperatures are 62 to 75 degrees C.

I can lower these temperatures by about 5 degrees C by removing the side cover and installing an old 4.5 inch ( 118mm ) fan. I had a fan with chrome protective grill set up to blow across the GPU's from about 6 inches ( 155mm ) from the inside of the front of the case. I also had ALL of the card slot knockouts removed so that the warm air can easily leave the interior of the case. I also had to clean the case out every month on a regular basis.

Because a computer acts like a vacuum cleaner I have changed my arrangement. I have sealed with tape ( painters or packaging tape works fine ) all vents except for the ones in the back and re-installed the side cover. The card slot knockouts are still removed. I took out the 3 blank plastic inserts in the front of the case right above the DVD drive and installed the above listed fan into the opening. I used double sided tape ( this is grey and sticky on both sides ) to temporarily attach the fan to the top of the DVD drive. You can use 3 or 4 layers of carpet tape but it is very messy. Both can be purchased at home improvement super stores. You will find the grey tape in the paint supplies in a red hang up style package.

Also in the paint isle you will find "Tack Cloths". To use one remove a cloth and unfold it until you have two layers left that are still stuck together. Cut out a section that is 6 inches ( 150mm ) square and lay it over the chrome protective grill and fold it around the sides. If the fan is running while you do this it will suck the cloth right up against the grill so that all you have to do is carefully adjust it for proper coverage. I have a GPS standard that I installed a cooling fan on with a tack cloth filter and after 3 years of operation it is still clean inside. When your internal temperatures increase by about 5 degrees C then it is time to replace the tack cloth.

Watch out for "Windows Updates". The last update updated my NVIDIA drivers and I have had nothing but grief since. It took me 2 and a half days to straighten out the mess that "Windows Updates" caused and probably about 50 corrupted W U's. I have also found that if "Windows Upates" is down loading at the same time that your system is down loading W U's it will corrupt all the down loads that occur at the same time and lock up your computer.

I hope this helps.
Jim