BSOD - Hardware error but cannot pinpoint

Hi All.

Started having random BSOD after installing new ATI Beta drivers. So, I backed up, and reinstalled windows 7. Same issues occurred:

Error is often: STOP code 0x0000001E
- Random BSOD, on Starting Windows, or once logged in (the max uptime is about 15 minutes)
- Random Windows errors, DLLs, Package errors when installing drivers etc
- On some BSOD, it only partially completes the screen, so do not get the full error
- Windows Desktop can freeze with corruption (multi colour lines everywhere)
- Random Freeze forcing a hard reboot

I have tried
- Changing GFX card
- memtest86 - memory passed (testing one stick at a time)
- Changing boot drive to a newer SSD
- Disconnecting all other drives other than the boot drive
- Reinstalling Windows (about 9 times in 24 hours)
- Reseating all devices and checking for loose wires/connections

When running outside of windows, there is no failure, so in memtest, bios, or DOS/Linux AV scan, no power loss or freezing.

This seems to leave PSU (which is 2 months old SuperFlower 80+ 750w), CPU, or Motherboard?
Really stuck as not knowing is going to cost me £300+ to replace all these parts

Thanks for the reply.

Weirdest thing. Even though I tested the memory individually, when I ran the machine with just one 4Gb Module, it works fine, no crashes as of yet. So I guess that's either one stick has 'a' fault, or the slot may be faulty. Will do some testing now and see if I can pinpoint what the problem is, or at least the results.

Thanks so far :)