You are working as a technician at Domain.com. You have been asked to replace a defective CPU and to ensure that the new CPU is functioning. The initial check seems ok but after several hours the CPU is overheating. Which of the following may be the cause?

A.
The CPU was not properly seated.

B.
No thermal compound was used.

C.
The thermocouple was not attached.

D.
The wrong CPU was used.

Explanation:
A badly seated CPU or a wrong CPU would not boot at the first place so those alternatives are wrong. A thermocouple is a heat sensor; it would not have anything with the overheating to do, except possible turning of the computer once it is overheating.
Thermal grease(also called thermal compound, heat paste, thermal paste, or heat sink compound) is a substance that increases thermal conductivity between the surfaces of two or more objects. In electronics, it is often used to aid a component’s thermal dissipation via a heat sink.