pain in the ass huh?
I read somewhere on the web, that the source of the problem is the gpu chipset gets hot which melts the solder holding the chipset. To fix that, you need to reflow the gpu chipset and it will be a permanent fix.
Some folks just replace the heatsink and add in paste and works for them. I say fill the system with 1-2 gallons of gasoline and attach a string and light it up (DO NOT TRY THIS AT HOME) which should fix issues.