if you look at the report that was attached, it shows it was not running that big of a load on the cpu. resources look normal to me. only the temperature was abnormal.
I do think replacing the thermo paste is needed, especially if its been overheating for a while (thermo paste can get brittle) when laptops run hot over a period of time or when sitting in storage for a while.
a couple other things that need to be looked at too. when the harddrive was replaced, was it a clone or system image installed, was the factory os that came with the laptop installed, or some other os installed. did you download the drivers needed from acer or some other site?
my mind is a bit slow at times so it may have been you or someone else, but there was a similar post in another thread not too long ago thread where i asked if linux was tried. If I remember correcting the response was linux was tried and it still had a heat problem. If it was you, then imo, it is not a resource, driver, or other software issue.