PC Games Hardware has a preview of the PC Build:
http://www.pcgameshardware.de/The-Witcher-3-PC-237266/Specials/Technik-Test-1158845/
German so a quick and dirty translation
- Preview build so no final benchmark
- GTX 770/R280X is enough for Ultra
- 2GB VRAM is enough
- Config files offer a lot of tuning (view distance, shadow resolution, texture size)
- Great multithreading (used all cores on a 4790k)
- midrange GPU and 3ghz 4 core (intel) CPU is enough for highest settings and good fps
EDIT: Saw it already posted in another comment. Ah well. Repeat for visibility then^^