Ok I checked cause it was playing on my mind
... took me a while to find the heatsink in the bottom of the box tho..... is it me or do Asus vga boxes keep getting bigger & bigger
anyway enough sillyness, there are four spring loaded screws on the front of the card:-
Just undo these and remove the complete sink it two parts with fans still attached. The four tiny screws just hold the anodised aluminium ram sinks to the copper base plate.