New mobo might not be possible in that case. I've seen a lot of mobos where they are physically matx sized, but the cpu heatsink mount screws are non removable from the case itself instead of a separate backplane that bolts through. By doing this they save another part and thus $. If the replacement mobo doesn't have the cpu mounts in the absolute precise same spot, the screwhole mounts will jam against the back of the new board, making fitment a no go, or else they put pressure and risk shorting the board. Otoh, if the heatsink mounting retention bracket is a separate removable piece, then I agree, a $70ish Asrock z97 matx board is gold. Will support 4790k ocing, better usb3 and sata6 performance, 4 ddr3 3000 slots instead of 2 1333 slots, etc. Following that path, simply buying a case and mobo would be still a valid option to consider if OPs case won't take a standard board.







