first don't get 570,second don't get 2600k/2700k if it's a gaming rig.2500k/3570k is best gaming cpu.
for a single gpu setup,a quality 550w~ is enough and for SLi/CF setup,a 750w~ is enough.
note:i suggested the power supply assuming that you are going to get H 7xxx/ GTX 6xx cards.
All of the below are better than the GS800 because they have lower ripple on the +12V rail(s). I also would not buy the GS800 in light of Corsair recently announcing/releasing an updated version which is improved in many ways.
Corsair TX750 V2 (£80 @ Dabs) http://skinflint.co.uk/616452
Uses the same internal design as the XFX Pro 750W Core Edition, so if the XFX is cheaper there aren't many good reasons to get the Corsair instead (and vice versa).