Another thing to consider dean.. or gabe.. or anyone whose on the ball with unisinks... ASUS has announced their TOP version of the 5870 (and 5850 later I assume) which will allow software voltage tweaks.. now this might mean non-reference PCB which puts the full-block option a pain for both you and the consumer, but a uni-sink is a lot better approach. Not to mention, it allows adding a fan onto the vrm area for additional cooling if needed...

correct me if I'm wrong, but no full-cover gpu that I've seen yet has flow over the VRM's