Is it possible to have 2 different GPUs not in SLI?
Like a GTX 970 and a GTX 760 and use one for each monitor but for still the same PC, 1 in game the other one on desktop etc.
Yes
I do this with a Fury and a W8100. Works.
Yep. This is how I used to run 3+ monitors many years ago.
yes it works no problem
I used to have two 660ti cards with no bridge for rendering in Blender. As long as they're on full 8x or 16x slots are from the same brand you won't have any problems.