it probably has epoxy not thermal tape.. you have a few choices...
1) Place a credit card between the chip and the heatsink... use a flat screw diver, and use a slight twisting motion... it takes a bit of effort but you know those boards can take it...
2) If that doesnt do it... place it in the freezer for 5 mins.... then do #1, it should work well
3) sand it down using 400 grit sandpaper and some flat surface...........
4)artic silver epoxy rocks...
anyway, just as a side note.... using a HSF combo on a vid card will probably not increase how much you can overclock it, and if it does, 10mhz at the max... thats my and my friends experience....
Old addage: "Users never prosper"
) Long live the tweakers