I took a lot of the components of my computer out to clean it, something iv'e done before. When i put everything back together and boot it, everything starts normally, but then after a few seconds the fan on top of the processor heatsink sounds like it goes into superspeed (LOUDER and faster), then a few seconds later the computer shuts down. I did take that part off to clean it and blow air down to get DUST out of the heatsink... 

Its a five year old computer and i'm planning to get a new one within months, but i need it to work for now. If anyone can help i would realllllllllllllllly appreciate it, thanks.


-Richis the heatsink clean? did you REAPPLY the thermal paste?well i didnt take the heatsink off, just the fan,.you may have damaged the fan. make sure the heatsink and fan are clean and properly reassembled, then try it again. when you pryed the fan off the heatsink did you make sure that you didnt cause the heatsink to lift off of the CPU? WORSE case scenario, you may need a new heatsink.
Thanks for the help. the heatsink may have lifted slightly but its hard to tell since i didn't intend to remove it.
should I BUY a new fan and test it? Or should i remove the heatsink first and apply the thermal gel?remove the heatsink first. clean both the CPU and heatsink surfaces with isopropyl rubbing alcohol then reapply thermal paste and remount. if your comp still shutsdown, then you may need a new heatsink.