Check the CPU temperature in the BIOS, from Advanced >> Hardware Monitoring.
Check the Thermal Specification for the CPU if it is still within the range of operation.
Get your CPU sl number and search in the link below.
If it is much over the range then, check the following:
Do a CMOS clear and Download the latest BIOS and update it thru recovery mode
Make sure that you have a PSU Atx Version 2.0/2.1 at least.
Make sure that the chassis is TAC - Thermally Advantage Chassis
Check for proper aeration in the chassis. (cable)
Re-integrate the cpu with new small amount of thermal paste (clean the cpu before)
Check and test the system out of the chassis and see if it behaves the same way
Hope this helps a bit.