You can go to a chemist and ask for Isopropyl Alcohol just like that, and you get a small bottle 50Mills for R5 here which is like $0.90
You can use Acetone as well.
Just put it on a cotton swab..(ball of cotton wool) and wipe over CPU and Heatsinks cleaning any crap off. Not necesary, but it will help with temps and it cleans little bits of dust off which then goes with that "microscopic valleys" thing.. more.
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