Another change is the addition of a cutout in the motherboard tray for the heatsink/cooler backplate. If you use the bog standard Intel cooler then this wont matter (or at least it didn't), but the after market jobbys which have a backplate will. The location for socket775 and socket 1055/56 are slightly different, and the sizes are too. Current ATX cases usually cater for the largest socket around, so socket2011, but an ATX case from 1995 would have no cutout for cooler backplates, except for one you cut yourself.