No, it wont make much difference. It probably wouldn't increase life expectancy if you frame cap. if you get over 100 fps then it means your graphics card is well up to the graphical demand of the game. If the temps are reasonably high though, then you could cap the fps at around 30 fps more than your monitor refresh rate, so the GPU wouldn't need to work as hard. Saying that though, the 980ti should be more than capable enough to handle high temps/fps, and would thermal throttle if temps got too high anyway.
Hope that helped
llamington