find the cause and eliminate it fast.

One possible exception would be if someone, in the BIOS, set the level at which the alarm sounds at a ridculously low temperature level.

You need to check the BIOS settings and open the computer and check that all fans are working at their full capability, not loaded with dust bunnies. Especially check the fan that is on the heatsink that is attached to the CPU. If you have a dead fan, be sure to replace it with one that uses ball bearings rather than the sleeve bearings that probably came with the system.