New
#11
yes on 14 year old cpu if the thermal paste has never been changed then you would want to change it. Its not crucial i only briefly mentioned it because the real thing is that you want to replug the CPU as a test but when you are there you might as well change the paste.
Computers work until they don't those CPU are cheap as chip you can always just get one from ebay and replace it.
The fan jolting like that usually means the computer is stuck so the CPU is not doing what it needs to do and the bios is not coming on. The jolting is because the CPU is resetting itself to try again. Generalization here but its along these lines.