silly question not having used da-vinci pro, but is it just something as simple as a tick box option like some adobe products where you merely haven't turned on GPU acceleration? Also update video card drivers. And you need some data to actually see the problem rather then replacing bits to see if it fixes the problem. even just simple task manager (on a newer Windows 10 build that also shows GPU Usage) will give you a good deal of info and point you in the right direction. you can then drill down even better in resource monitor.