Using dual monitors on different graphic card isn't really beneficial in my opinion. It's basically putting the load on the iGPU (CPU) instead of the discrete GPU. Therefore your GPU can have more headroom when needed, but the difference is minimal especially when you can't game on a Intel HD at the same time anyway.
The set up is pretty much going to be Intel HD just displaying some static image like a website while you're playing on the other monitor using GTX 630.
Again, the difference is minimal and I don't see a reason why to not connect both monitor to GTX 630.
Just my opinion.
Thanks its pretty much what I could tell from messing with it for the last few days. Thanks for your time its appreciated. Been reading posts here for months and it was nice to put something up and not have to piece together what I was trying to figure out from thirteen similar posts.