I'm having some issues with my gfx overheating. I currently hit 80 celsius on heaven benchmark even when I limit power to 70-75% tdp and use kboost. Without any limits/Kboost it throttles itself to 65-70% tdp. While this is happening vram temperatures are around 50-55 celsius. This is with no overclock.  I also have a Fractal Design R3 case with fans blowing air front, below, above (over ram sticks), with exhausts to the back. I dont think case airflow is the issue here. The fans also do not seem be blowing much hot air out from GFX. 
 
I'm thinking of removing the fan and heatsink from card to reapply some thermal paste. Can I do this without ruining the pads? Is regular CPU paste usable?

Card model: EVGA GTX 780 Dual CLASSIFIED w/ ACX Cooler, Asic quality: 76.3%.
 

Thanks for answer. Also got help from Evga support. I changed the paste on gpu die and temps dropped like 35-40 celsius. Max load is more like 58-60 celsius now (whereas 65-70% tdp hit 80 celsius before). No more 65-70% tdp for me!