After few hours of work I have reached here.
I might have to do all the cables again sometime in future. Cables from H100i block are just lazily tucked underneath the radiator fans. I need to take the whole block out, pull it apart and thread the fan cables from side of fans whilst mounting fans to do it properly.
Another thing, If anyone had problems with front USB (2) on R4? I've tried different headers but it is still same. It takes forever to be detected or something like that. I get A4 on debug led and monitor before it posts and slows down my booting time by about 15 seconds.