Xmas Present Build, Small PC Format

Ladies & Gents, as xmas is right around the corner I wanted to give a gaming PC as a present to my gf as she is into gaming but she has one of those apple laptops(thats no bueno), and I have recently updated my pc and I have some spare components:

2xKingston(2x4gb) 8GB RAM, 1xAsus R9 280x GPU, 1x Corsair 600M PSU, 1x CM 212 evo CSU(but I doubt I would be using it, since I am looking for a small format build. I was planning to build a small format, MATX, Mini ITX, or an ATX but atleast with a compact case. I have an AMD fx-6300 CPU laying around, and apparantly I cannot find a small format mobo (or atleast I can't find any here in the UK), so I decided to keep that aside, and go for an Intel CPU, but I don't need no i7-3770k or 4770k or etc. The PC would just be for mainly gaming, and the daily stuff(social media, movies,etc.). The PC case is another thing that gives me a little bit of a hard time, I remember, a long time ago that she saw the Corsair Graphite 380T and Bitfenix Prodigy M and she likes the format, so if preferebly I can stick the build into one of those it would be awesome!

So here is where I ask for help,
I would like to know if I can use a CPU like the i5-3570k, or is it too outdated, and if it is, could anyone recommend me an entry level CPU that wouldn't be too heavy on the wallet since she won't be gaming hardcore(ie: Skyrim with 50+ Graphics mods) (intel CPU preferebly due to mobo size availability) a small format motherboard. HALP!

Project Kampas Krismas Build Part List:


CPU: N/A

CSU: Stock Cooler Fan atm.

Mobo: N/A

GPU: Asus r9 280x

Ram: Kingston Beast 8GB

PSU: Corsair 600M

Case:Corsair Graphite 380T or Bitfenix Prodigy M

 

I'm all eyes and ears for recommendation for CPU's & Mobos.

 

Sorry for long post and thanks in advance!! :)

For mini-itx  there is no AMD AM3+ option for that. also m-ATX boards, there are not realy decent m-atx am3+ boards unfortunatly.

So if it has to be mini-itx or micro atx then i would recommend to go with intel.

i would personaly recommend an i5 anyway. because it will perform better in cpu bound games like mmo´s and indie games.

This.

An i5 and a M-ITX board would be good for a SFF PC.