How high quality do you want the videos to be? You'll need a fairly high bitrate (20k-40k) if your settings demand it. Personally, I would advise going for the x264 encoder (CPU if you don't have that), given that your processor has 12 total threads. Your GPU seems to be the weakest link in your build (aside from the RAM), so I wouldn't recommend using the GPU encoder unless you don't feel a performance loss.