still can't take it off? put it back in and play C3 or something for about 15 minutes. shutdown, then take it out. do not rush 'cause it will still be hot. undo all the screws and twist slowly the cooler from the pcb as described by Ranger.
edit: btw, there are coolers that are attached to the bracket (used to hold the gpu to the case) using tiny screws. check it out.
Edited by rdr09 - 7/29/13 at 1:18pm