VRMS were placed on these cards instead of having capacitors.
You will see 4 little holes around that area where a VRM heat spreader can just screw in even though you are currently using the Sapphire reference cooler.
Have a chat over at the HD2K clubhouse, the users there are more than happy to help you out with what would be the best cooling solution for your VRMs and I'm pretty sure one of the guys has installed a Zalman VGA cooler with the heatsinks your'e talking about.
There is a pic of it on the first page iirc. . .