CPU is overheating

Did you remove the CPU heatsink and refit it using thermal paste, then refit the power to the header on the motherboard. This is usually the fan it refers to

start by removing everything, ram, any cards plugged in, drives etc. Then try and boot it. If the issue is still present, shut it down and remove the heatsink and cpu. I have known CPU's to be jolted out of their sockets after an impact. Take the heatsink off, lift the lever and remove the cpu. Check that all the pins are still aligned and straighten any bent pins then refit the cpu and lock the lever down. Refit the heatsink making sure that the heat transfer pad or heatsink paste is still present and lock it down. Plug the power cords and front panel wiring back in and try and boot it. If it boots, shut down and refit each item you removed one at a time, booting in between each item. If the issue arises again, the last item you fitted is the culprit. If you can refit everything and boot the system up, lady luck is with you. If you still cannot get it to boot after refitting the cpu, replace the mainboard. Sorry but without special gear, locating a fault like this on a mainboard is a real pain..

The Compaq C300 laptop most likely is overheating and shutting down (ie thermal overload) and will not bootup again until it has cooled down. If this is not fixed eventually the CPU will fail.
The overheating is caused by a faulty fan and/or dust clogging the heatsink and fan assembly.
Check the fan to see if it spins freely (replace the fan if it is faulty) and use a stiff brusk to loosen the dust from the fan and heatsink and vacuum the dust from the fan and heatsink.
If you remove the fan assembly from the CPU then apply fresh thermal paste to the heatsink pad before placing it over the CPU.
The laptop should be placed on a flat surface so the vents are not obstructed. You can also place the laptop on a fan assisted base to provide additional cooling.

Either CPU is faulty, or the heatsink has lost aderence with the CPU surface or coolin power.
Atandardprocedure is refitting or replacing cooling fan, in some rare occasionis the CPU, but that is uncommon and can't be tested.
Another possible cause is the temp sensor on the motherboard that is faulty.
first ensure that is overheating and check temp sensor using SpeedFan - Access temperature sensor in your computer.

Either CPU is faulty, or the heatsink has lost aderence with the CPU surface or coolin power.
Atandard procedure is refitting or replacing cooling fan, in some rare occasion is the CPU, but that is uncommon and can't be tested.
Another possible cause is the temp sensor on the motherboard that is faulty.
first ensure that is overheating and check temp sensor using SpeedFan - Access temperature sensor in your computer.


Good luck.

G.