ALL CAPS BECAUSE IT MAKES A SENSE OF URGENCY! BUT YEAH $650 GAMING PC BUILD! INTEL CPU, GPU DOESN'T MATTER! GO!
LOOK, A ROCKET SLEDGE http://pcpartpicker.com/p/bFBLbv
....boring build for boring people http://pcpartpicker.com/p/ZFwgCJ
JK, but please put some effort into your original post before you submit it.
my advice ... save up more money
you said CPU does not matter
Save up or this - https://teksyndicate.com/forum/linux/cheap-linux-gaming-pc/186629
If need be just add a windows licence on for about $100 or what ever it is outside of UK