Goof-off or any xylene-based cleaner will work well. Just make sure that you do not use a scented cleaner (citrus Goo-Gone) , and for the love of Pete, do not use WD-40.
Also, If I am interpreting your post correctly it seems that you could rip the KIA CPU off the heatsink, just don't scratch the HS base.
Black, huh?... how old is it?
[SIZE=\"1\"]E6400 @ 3.4 , Noctua 120
7900GT @ 670/1680 , VF900
2 x 1GB Patriot 6400 @ 425
WD SATA 250GB
Neo HE 550
P180 / G15 / MX1000[/SIZE]