I have a Pentium 4 3.8 GHz machine mainly used for backup, and the BIOS reports temperatures of almost 70C within 5 minutes of startup! I have replaced thermal paste and added a 10000 RPM Delta screamer and that only dropped it to mid-60s. I was wondering due to its age the problem could be the TIM between the die and the HS. Is the HS soldered to the PCB or just adhesive?