What role does the GPU play in UE4 when compiling?

FX 6300 scores a 6,356 on PassMark - CPU Mark
4130 i3 scores 4,813

I’m looking at getting a i7-5820K myself. In straight up multi-threaded applications like rendering and baking AMD processors perform pretty well and are cheaper, but when it comes to single or double threaded applications or games, I’d take a i5 over even a higher clocked 8-core AMD processor.