MetaTron, you have several test utilities just to verify memory (only memory). Usually these programs runs booting from a floppy. Dont remember the names, but looking for them should be easy. BTW, if you have reboots only with 3D games running, then your problem my be related to your graphic card instead of your memory. Do you have a temperature sensor for your card? If not, try to open the case and run the same games. The problem may also be related to power supply or even chipset AGP driver, but rarely to graphic driver itself, AH is not so "complex" to suffer from modern driver issues.