Yea, like I said, if you cut the little plastic grill off, it's more likely to fit a rad. It absolutely won't happen with the grill in place though. I can tell you that. If you're mounting an H100 rad, it's a pretty thin rad, and it should work out. Any reason you want it up there? Most of us mount the rad on the top below, and then mount the fans above it in the grill area.
"One man can change the world with a bullet in the right place."
"Life can never seem so real as when it faces extinction"
-U.S Marine Corporal Ron Szpond, Vietnam - 1966