You're not putting thermal paste on a product that has active cooling...
Active cooling and thermal paste.
I could also claim to know a lot about disassembling and finetuning car engines cause I got a car.
Doesn't make me an expert in it.
Without firing shots.
You should ALWAYS put thermalpaste on heatsinks, especially if they have active cooling.
Also, seeing it's a 2007, it's likely to be a Zephyr.
Without an expensive reball, the RROD will come back again.
It's a waste of time and money trying to fix it.