Artic Silver Silver Adhesive providing it'll fit. I use that to mount a SS7
HSF to a GF2 GTS

I wouldn't use that. Its too messy and too much risk. I know its better
thermally then everything else, but I found its hard to work with. I find when
you try to attach heatsinks they slide all over the place and the stuff goes
everywhere which is not good because its slightly conductive.
I would use Artic Alumina Adhesive instead. It is super strong and it seems to
dry quicker and grab onto the heatsink without it sliding all over the place
as you apply pressure. Its not as good thermally as Arctic Silver adhesive, but
its close.