M-itx gaming build

Hi all,

I'm going to be putting together a m-itx build in the coming weeks, and am looking for some opinions on what to spend my money on. My budget is £600-£700, although the lower the better really. The good news is I already have an HD7970 and a 2650x1440 IPS monitor, so that's a lot of money saved.

I want a small, portable and powerful build to take between home, uni and friends houses, hence the ITX form factor. My primary use will be gaming, and from experience, things that are good at gaming tend to be good at most other tasks as well.

I'm leaning towards a lian-li case, as I like their looks, and build quality. Namely the PC-Q18 or PC-TU200. I'm prepared to spend a bit more here. The Bitfenix prodigy is a bit large for my tastes.

What I'm most stuck on is what CPU/MB to go with. I can't decide between the following;

Intel

Z77 chipset + core i5 xxxxk
non-Z77 chipset + core i5 or i3

AMD

FM2 chipset with 5x00k or 750k

I'm not fussed between Intel or AMD, but I do want enough performance to drive a 2560x1440 monitor, as well as not starve my 7970.

I'm unsure weather to get an i5-k series chip due to the cooling limitations in the case. But paying £130+ for a non-K chip seems a waste. Is an i3 enough to run demanding games at high detail, or are 4 cores needed? The i5+Z77 setup is expensive, and if i can get away using an i3 or an AMD FM2 quad then the extra saved could be put into an SSD, which i'd like. I'm also willing to mod something like a Corsair H90i into a case to provide extra cooling, should it be needed.

Sorry for the long post, any thoughts much appreciated.