Hello, and welcome to THG.
Seems you need to reseat your Heatsink. Remove the current heatsink and clean the CPU form thermal paste. Apply an new layer of thermal paste and put the heatsink on FLAT. Try to use a screwdriver to push gently,( but firmly) into the holes. Do this in a cross-like pattern. When the screws feel tight, stop and gently tug at the HS. If it feels loose, try again o screw them in, if not...you are cleared.