When you push the heat sink on the dot of IC Diamond it spreads. That is one source of movement. Another source might be from the liquid getting hot. Atoms move around faster when they are heated, but I don't know if that would be enough to cause micro scratches like that. They even recommend to do that for proper application and mention a break in period which occurs afters the liquid gets heated up so it can spread better.
I am slightly worried. I'm still using the IC Diamond and haven't bothered to check if any damage has been done to my heat sink or CPU. Performance has remained roughly the same so haven't had a reason to check until reading the above posts. Aside from the scratches which could be sanded out that dent is pretty large :/
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