Is the thermal compound electrically conductive? If so, make sure to not put it on the transistors. But if its not conductive, you should be pretty generous with the paste, the normal dot method doesn't work on gpus because theres already a heat spreader on cpus so it allows for a little bit of surface not in contact with the heatsink. However, for a gpu, the die is directly touching the heatsink, you have to make sure every last bit of the die comes in contact with the thermal paste. I would recommend the line and dot method but keep in mind that use a little bit more than what you would use on a cpu. The finger application method is also adept if you make sure there are no air bubbles.