For motherboard, I would highly recommend to get ASUS Maximus V GENE because of professional OCing options and stability that you will require as your processor is made to OC.
CPU|Everything for your budget|Intel i5 2500k|12k
Motherboard|If you DON'T want to OC|ASUS P8Z77-M PRO|13k
Motherboard|If you WANT to OC|ASUS Maximus V GENE|15k
And the ASUS Maximus V GENE is my favorite sub 16k Motherboard too..
ok....then what about PSU? i have vx 550
LOL the Z77 chipset allows Overclocking!! Research more before recommending anything
@OP get either ASROCK Z77 Extreme 4 or ASUS P8Z77-M Pro. Both of these boards are good overclockers and great performers at their price range.
VX550 for crossfiring HD7850 is NOT GOOD. Change to atleast Seasonic S12II 620W or Corsair HX650.
AsRock has some LLC issues. Better to skip that imo.