the Ultra-D is kind of a SLI board, it has two PCI-E slots, but it's bandwidth is different than SLI...theres an easy mod though that can turn the Ultra-D into a SLI board.
His voltage is fine as long as he keeps it cool codeine. I have to use 1.85 through my stock 1.35v XP-M to get 2.5GHz, yes it's a much bigger OC than his, but still I've put 2.225v trying to get 2.8GHz stable....the older chips need a good amount of voltage and his particular CPU isn't known to be a great OC'er by anymeans, so as long as it's cool it's aright....but he needs to make sure that that's DEFINITELY his limit as far as voltage per Mhz go