So im cleaning my loop today for the first time and everything looks good. But i thought that i should swap the thermalpaste and also see if i did it right the first time and find this "burnmark" ? on the block (the cpu looks fine) so i cleaned off the paste and the mark won't come off.
thermalpaste used is Arctic MX-2, and i did clean the block before installing it. temps have been fine (never over 60c i5 3570k at 4.2) ideas? should i just put the loop back together ?