Depending on what CPU you have, your really could be putting more stress on it than your GPU. Generally it doesn't add any stress on your GPU. The more monitors you have the easier it is to multitask, hence use more cores on your CPU.
An i7 is definitely the way to go for any kind of editing or rendering thanks to their hyperthreading. I suggest you either get an i7 or go all out and buy an i5 with that cpu cooler. I just hate to see that i5 not being OC'd, especially when it is being used for editing/rendering etc. Depends on what it most important to you.