Gateway LX 6810-01 desktop computer it cuts off every 15-minutes

[Websurfer]

While fixing a Gateway LX 6810-01 desktop computer it cuts off every 15-minutes. I ran system diagnostics and checked for virus issues. After resolving all virus/malware issues by reinstalling the (windows 7, 64-bit) operating system, seating the ram and changing the power supply, the computer continues to cut off after the computer’s case was reapplied.
Moreover, a quick inspection of the cpu and fan settings in the bios shows the computer is cutting off b/c its reaching in excess of 75-80 when the cover is attached. I placed a small fan on the cpu and watched the temperature go down to 70. But this room fan is only a temp fix to prevent the cpu from damage while I inspect the thermal paste, exchange the fan, and add another if necessary to bring the temp into normal specs. While in bios I was unable to adjust the fan settings. The MBO has a 3-pin and 4- pin for fans. The four pin is in use for the cpu fan. I ordered a 90mm, 12v 3-pin fan. I just want to know if I covered all bases? Any ideas?

 

[arges86]

Well, it seems you found the culprit
Heat is the worst enemy of any system.
If you have the budget, aftermarket fans are always great, they are quieter, cooler, and don't cost an arm and a leg.
Make sure you get high quality therm paste... i usually use Artic Silver http://www.newegg.com/Product/Product.aspx?Item=N82E16835100007

When configuring the case fans, make sure there is no dust on the filters.
I've found its best to have more air leaving the case than entering. It creates a lower pressure in the case which helps dissipate heat much quicker. the graphics card, memory, hdd, ect... they all produce heat too