The "UD" in Gigabyte's boards stands for "ultra durable". They supposedly use better capacitors in them as well as a few other changes. They've always worked well for me (except for the issue with Corsair XMS3 RAM not working with my i7 950 due to the wrong speed and the BIOS not acknowleding all the RAM that was installed, but since the RAM wasn't on the MB's approved RAM list, I really can't complain too much.)