The board should mount without any issues; be sure the power supply leads off your old dell ps match or you may have to change that also. If you have a case standoff that doesn't line up with one of the holes, remove it. You only need 4-5 holes to line up to mount the board. Locating a backplate for the c27vv may be impossible; I doubt dell sells them, and most venders don't include it. You may have to leave the ports exposed without the plate, also called an i/0 shield. I sometimes post a request for an old part on craigslist or anandtech. Finally, you may have fewer issues if you purchase the whole original case with the newer board on ebay, which should have the backplate, and not cost that much than just the board itself.