What causes a stress test to fail?

[maxland]

I got my old i7-920 clock up to 3.78. I'd like to go into the 4+ range but stress tests fail (prime95 and CoreDamage). I can run Heaven and get great results if I clock to 4.1 but can't run a single test with prime95.

Will a liquid cooler get me there?

 

[skit75]

3.8GHz is about all I ever got out of mine, with the same results as yours. Benchmarks seemed OK but stress tests had no chance of passing. I didn't fight it too hard. I just figured I lost the 4.0+GHz silicon lottery. Probably too much jitter being introduced to be stable. I can't hate though. This is the best CPU I've ever owned when all is said and done.

 

[synphul]

Heat can cause a stress test to fail. Also trying to push a cpu too hard with too little voltage (like a car running out of gas). There's a balance though because you can't just keep adding more and more voltage. Even if heat isn't a problem a processor or the motherboard might be limited by voltage. I'm not overly familiar with overclocking the i7 920 but I found some guides on overclocking it that may be worth reading.

http://www.techpowerup.com/forums/threads/overclocking-the-x58-a-practical-guide.108526/

http://www.bit-tech.net/hardware/cpus/2008/11/06/overclocking-intel-core-i7-920/1

http://www.overclock.net/t/538439/guide-to-overclocking-the-core-i7-920-or-930-to-4-0ghz

It might be better to have a more thorough understanding before pushing it harder or attempting to add a water cooler, especially if you're running into stability issues.

 

[KKAW]

Heaven has not much to do with cpu its a gpu benchmark and heaven and valley is not exactly the stress test. There may be many variables. Lack of voltage on cpu, lack of voltage on cache, unstable cpu in general, limit of cpu, temp cap from mobo or others.