I have applied thermal compound about 5 times so far with different results each time. If you don't get enough paste on them they will get hot and to much and they get hot. If the chips get to hot they are going to shut down. So the board you have that's down could be from the chips getting to hot. Reason I say that is one time after I reapplied the paste I had a chip shut down as soon as the stats came up from getting to hot. I redid the paste once again and it came back. Finding the right amount of paste is the trick since the four die's are not level. I'm yet to get it right.