At this stage it could still be anything.
I am afraid we need to simplify the test programs to get rid of the RAM altogether and to prove the kernel ROM, CPU and video RAM.
Basically, a pure and simple test program that constantly writes the same thing to the VDU memory but provides some feedback that things are still working.
If that runs for a very long period of time, then you probably have a RAM fault and we can then concentrate on capturing that.
But you can do that yourself by buying Nivag's ROMulan RAMulator as I have stated previously.
That should rule out everything but the RAM...
Incidentally, was the keyboard PIA in or out when you took the photograph in post #597?
Yes, the voltage regulators will be hot - but very hot is not descriptive enough... Remember the voltage regulator on your monitor?!
Dave