I love the fact that the 4670 heatsink has a PCI-type connector - presumably to prevent excessive stress on the screws holding it to the card!
As far as heatsink sizes go, I don't think we've seen a passive 4670 before, have we? I know Sapphire did a 4650, but they fairly significantly down-clocked it to passively cool it. This is a full fat 1GB 4670 running at full tilt - I'm not surprised it needs a hefty heatsink!