Regarding grey rubberized thermal covers.

Do these require heat sink grease? I did not think so but they always seem to have some when I find them.

Also...Does Heat sink grease (White kind) become conductive? Seems like it might if it was ground up microscopic flakes of titanium etc.

Thank You.

If its rubberized then it will conform to the shape of the surfaces so grease is
unnecessary (that's why its made flexible).

White heatsink grease is usually zinc-oxide filled or similar - the entire point
is to not conduct electricity or you would use a copper-filled grease (as used on
car disc-brake pads to prevent squealing)

Is what I thought about the rubber too. Thanks for the info on the White Grease.

That stuff doesn't need the grease - it's meant to replace it.

Thermal compound can have ZnO, but Al2O3 ("arctic alumina"), metal nitrides, metallic silver ("arctic silver"), and even diamond (really) are also used in readily available higher performing thermal compounds. Most versions of silver thermal grease are non-conductive. I thin