|"HERE are my specs"|
You mean, "here are some of my specs". If you want help, you need to list ALL your specs in detail. You didn't list the make/model of your CPU or motherboard, the type/speed of RAM, or the specs to your 500W PSU. Besides that, none of this has anything to do with CPUs or overclocking, so you're actually asking in the wrong forum.
Two likely possibilities are your CPU is overheating under load, or your PSU is inadequate. Also, the 8500GT isn't much of a gaming card so keep your game settings & game resolution set low.