I am looking for a small case to take to uni since my current case is too large (cm stryker). I have been looking at the define s since the r5 has more hard drive caddies which I do not need. I have one ssd and hdd and I use a mini itx mobo with a noctua nh d14 with an msi gtx 770.
I have tried a bitfenix prodigy in the past but I had problems with clearance on my GPU.
That's Mini-itx it should fit your GPU just fine. Not sure what cooler you have, but even a SilverStone SG-13B might fit the MSI Twin Frozr. Really squishy case though.