As you can see, the EK block has a bolt-on aluminium part to cool the power management chips. This is an excellent addition and is certainly needed with the newer cards such as the 7900GTX.
Closer into the block you can see the top of the GPU contact area. The block utilises 7 wave channels or "fins". EK say:
"The curves increase cooling surface and increases turbulence. The turbulence in channels reduces thickness of laminar flow which significantly increases cooling performance compared to straight fins."
Here you can see them: