Determining cause of Linux kernel panic

I’m running an Ubuntu 12.04 derivative (amd64) and I’ve been having really strange issues recently. Out of the blue, seemingly, X will freeze completely for a while (1-3 minutes?) and then the system will reboot. This system is overclocked, but very stable as verified in Windows, which leads me to believe I’m having a kernel panic or an issue with one of my modules. Even in Linux, I can run LINPACK and won’t see a crash despite putting ridiculous load on the CPU. Crashes seem to happen at random times, even when the machine is sitting idle.