Help With BSOD Troubleshooting

[Muel]

Hey guys, I'm having some trouble with BSODs at the moment, it's happened twice today already and I've no idea how to sort it. When it happens, the screen goes all scrambled and the noise from the speakers sticks on a ultra short loop, exactly how it did when I used to overclock and it wasn't stable.

Thing is I don't overclock now and haven't for a long time, it's been on stock settings for months. My temps are fine, I disabled C'n'Q to see if that did anything and it still didn't.

Running Windows 7 Professional x64, just reinstalled in January, and I'm very careful with what I install and keep it clean etc.

 

[Muel]

OK I set Windows so it didn't reboot on BSOD, here is the error:

*** STOP: 0x0000007F (0x0000000000008 etc

According to the Microsoft site, this is a Double Fault:

Double fault
A double fault occurs when an exception occurs while trying to call the handler for a prior exception. Normally, the two exceptions can be handled serially, however there are several exceptions that cannot be handled serially and in this situation the processor signals a double fault. The two primary causes for this are hardware and kernel stack overflows. Hardware problems are usually related to CPU, RAM, or bus. Kernel stack overflows are almost always caused by faulty kernel-mode drivers.

So basically I'm none the wiser. I'm running memtest at the moment on one stick at a time, no idea really how to test the CPU or bus?