To test the stability of overclocked CPU, download the latest bug fixed version of Prime95:
http://www.mersenne.org/freesoft.htm
Double click on PRIME95.EXE to start the program.
Just Stress Testing (if prompted) > OK >
Options > Torture Test > Blend (if prompted) > OK
The program should not give any errors.
It may be necessary to run the program 12-24 hours to make sure an overclocked system is stable (no program errors displayed).
If you get errors only after several hours, this is a result of slight instability because the system is running with little or no margin. It's stable enough to boot and to be moderately stressed, but as soon as the system is under enough load to go over that critical point, it will freeze. To be 100% stable, Prime95 should run 12-24 hours without any errors.
The point of testing is to see if you get errors or not thus testing the stability. The meaning of errors themselves is not as important.
Running Prime95 Torture Test for 5 to 30 minutes is enough to get a feeling about general stability. If it seems to be stable, increase the FSB (with 0.025V Vcore increase if needed), or increase the multiplier by 0.5.
Reboot and run Prime95 Torture Test for 5 to 30 minutes and repeat this until the Program displays errors.
It's then time to back down and repeat the Torture Test until there are no errors for at least 12 hours.
It's OK to use the computer while Prime95 Torture Test is running in the background.
After finding your stable point you may want to then retest by going to the Advanced section, setting the password to 9876 and then setting Priority to 10. (You won't be able to use your computer while Priority 10 Prime95 Torture Test is running, but it'll confirm your system stability.)
Use 3DMark to test video card stability.
