GPU's are generally much faster than CPU's at rendering as that is what they are designed to do.
So if you ask about video rendering, a GPU should be faster at it 90% of the time.
EditIt also depends on the program. Vegas, I believe, has an option to make the program GPU accelerated. Meaning your 980 is faster than your CPU if you are rendering with Vegas with that option on.
If you ever decide to switch to Adobe Pr, a Powerful CPU is bound to be faster.