If that was the reason then everyone who used
@scope666 EFI would have kernel panic. The same version of VirtualSMC or similar versions are used by almost everyone who has a hack. I had the same board back when he started this thread and jump started my build using his uploads. I never had anything close to what you are experiencing, never had a crash. There's something very, very odd going on with your hardware IMHO.
Did you ever do the memory stress test?
I took out some of the device properties for the iGPU, doubt it will make much difference but you can try it.