Mini itx or mid size computer. What is this itx capable of?

[Cstone]

Right now I've setup what I think is a fairly good mid size gaming rig but I've also made a mini itx as well. I just want to know what kind of games I'll be able to play with the mini itx. I'm up for a totally remake of the itx, just something I put together for a rather cheap price IMO. Not sure what it would be able to handle though and I heard that they can over heat easily. I'd just like to play some newer games, hook up to the tv, and just have a good experience as my first custom computer

Mid size
Graphics- GeForce GTX670 Asus 2gb
Case- cooler master storm enforcer
Proccesor- intel core i5 3570k
Motherboard- MSI Z87
RAM- crucial ballistix sport 8gb
Power supply- Corsair 750w
Storage- WD elements 2tb
DVD- Lite-On DVD burner
Price- $1077 and doesn't have any extra fans

Mini itx
Graphics- SAPPHIRE 100357LP Radeon HD 7750 1GB
Case- bitfenix prodigy
Processor- Intel Pentium G2120 Ivy Bridge 3.1GHz LGA 1155 Dual-Core
Motherboard- ASUS C8HM70-I/HDMI Intel Celeron BGA1023 Intel HM70 Mini
RAM- Crucial Ballistix Sport 8GB 240-Pin DDR3
Power supply- Not totally sure about this
Storage- HGST deskstar 1tb
DVD- Samsung internal slim
Price- $499.18

 

[Cstone]

One other question is can you put a better graphic card and processor than what I have? Is there any way to get better graphics so I can play games like skyrim on max?