I've got a strange problem with a DQ67EP board here.
System was running fine for roughly 18 months. A few weeks ago, the system started to occasionally power down unpredictably. This gradually became more frequent. After restart, the board indicates a "Thermal Trip" error (warning sound, prompt on screen). I've done the obvious steps: verified the case ventilation, checked seating of HSF, then reinstalled the HSF and applied new TIM. No improvement.
Current status: board is on a test bench connected to a PSU and to a KVM. It starts, I can go to BIOS and e.g. enter the fan control and hardware monitoring menu. Temp reads roughly 50 degrees Celsius there. After a minute or two (indicated temperature barely changes) it powers down. On restart, same Therm Trip warning. From all I can tell there is no reason and no real indication the CPU runs hot.
Any ideas? I've never had a CPU only go "half" wrong in all the years building systems (FDIV bugged Pentium excluded ;-). So current suspect is the board.