i5, skylake if you can stretch, & mobo. if i had of seen this topic earlier i would have advised saving the gfx card money and buying a cpu and mobo first. i went this route and play tf2 using the onchip gfx at a steady 150fps default settings untweaked (tomb raider at 50 fps
). theres news of a new AMD cpu to launch tail end of this year if you can wait. right now intel are crushing them, really, with most advising save your money if going the AMD route buying the processor (or at least from the phenom range) you already have.
my i5 6600k came in a bundle from scan.co.uk with a mobo, case and psu for around £350 (value individually +£400 and some) on the 'today only' deal. i got a great deal and made a big saving.
heres the bundle sections where you might find a combo deal seeing as you dont need as much as i did:https://www.scan.co.uk/3xs/value/valuebundlesspec#anc
, or, there's also aria.co.uk who do bundles too http://www.aria.co.uk/Systems/Bundles/
(mobo, psu & ram). both would be my two recommendations to look at. they have great sales teams that may tweak your order to suit, or, at least negotiate should you prefer something slightly different. as they're 'value bundles' they might be a little less forgiving though.