Asus aren't the only company doing an overclocked 5970:
Say hello to the Sapphire 5970 OC 4GB
http://www.fudzilla.com/content/view/17873/1/
The cooler is 3 slots wide, but it's Arctic cooling, and it should be reasonably quiet.
Say hello to the Sapphire 5970 OC 4GB
http://www.fudzilla.com/content/view/17873/1/
The cooler is 3 slots wide, but it's Arctic cooling, and it should be reasonably quiet.

. Do I really want to risk a £550 card for a bit more overclocking headroom? If I do then I'll probably wait until the next gen of DX11 cards are out (from both nVidia and ATi) so that if anything goes wrong I can use it as an excuse to upgrade... hopefully prices will be cheaper as well should anything go wrong. Grrr.