Appleinsider just posted this roundup of ifixit's teardown. Apparently the iMac has the correct amount of thermal paste 
And removable graphics board!
http://www.appleinsider.com/article...rbolt_imac_find_removable_graphics_board.html

And removable graphics board!
http://www.appleinsider.com/article...rbolt_imac_find_removable_graphics_board.html