It may even be beneficial to use CPU render only
That is only an option when using Cycles, I think; Eevee always uses GPU as far as I know.
Had a GT 630 before (until about one and a half year ago) and that struggled with Eevee and Cycles was slowed down tremendously since Cycles X.
If you are getting a newer GPU (which will probably mean a new computer), also look at the GPU RAM; I believe the 660 has 2GB, that is not a lot (for graphical software). I have 4GB now, but that is still quite low.
