I play the witcher 3 on:
Athlon 64 X2 3800+ (Windsor, Socket AM2) with light overclock to 2200 Mhz, runs stable at 50-55°C
Gigabyte Geforce GT 630 2048 DDR3 (not Overclocked)
4GB Ram
I tweaked the Witchers User.ini to lower tesselation, Speedtree, and Decals (Decals are additional cosmetic...