The CPU hot led should be triggered when the processor overpasses the maximum temperature allowed in the systems. The normal temperature may be from 30 to 45c under normal workload and it can go up to 88c with heavy workload. In the case the processor passes 92C it is considered as overheating and for security purposes the system will automatically shut down.
If you are still having this problem after doing the recommended troubleshooting steps, I would recommend you to contact the Computer Manufacture for a possible product replacement.