Media PC for casual gaming

[almightydutch]

This comes around often enough but a mate has asked me to spec him a media PC for his bedroom but something that he can casually game on.

Doesn't care about noise when gaming but wants it near silent when streaming 1080p vids etc.(I know I know, slightly moon on a stick content)

Hes asked if I can prep him 2 systems, one with a budget of £700 and one with £1000

I've been running through systems and I just cant seem to get a decent enough spec for his budgets. The £1000 system hes asked for a GTX970 as he has a 4k screen up there and wants to use it to its full potential. I've been through so many baskets I'm going mad so I'm asking for a bit of help from you guys to point me in right direction

 

[almightydutch]

Smaller the better to be fair but not restricting him to purely SFF cases.

Nice wireless media type keyboard would be nice but he does already have a Media Centre remote and Xbox pad so its not essential.

O/S Wise yes it requires Windows but the budget is purely for hardware