What are CPU temperature hotspots and why do they occur?

Transistors inside the CPU are distributed over the entire surface of a chip, but they are not all equal. There are different CPU areas charged with different tasks.

For example there are the cores, the shared L3 cache, interfaces, and others. These sections have different surface areas exposed on the chip.

When a task comes in for computing, this data goes through these areas where it gets processed. To complete the task the CPU needs a certain amount of energy.

Modern CPUs also have very specific processing for specific instruction sets and they process them very efficiently thus increasing the energy consumption even more.

An area of the CPU that is allocated to a computing task that consumes a significant amount of energy will become warm, causing a hotspot. These hotspot areas are common on most modern CPUs. By using hardware monitoring software like HWiNFO64, you can see in real-time the hotspot temperature.