Umm, games and things like 3Dmark arn't going to do it. SuperPI is getting closer, but that's still not intense enough. Games and benchmarks like 3dmark stress the video card, and while they do put a good sized load on the CPU, they do not do it nearly as well as a program that is made to test just the CPU. Prime95 is vere popular, if you are prime stable for 8hours or more, then you can consider your overclock "successful". If you want to go the extra mile however, I would download a program called S&M. It puts an even larger load than prime95 on your cpu. just google for "s&m cpu".
so, umm, err yeah