Overview of Processor Thermal Parameters and Their Meanings

The processor is a very important part of your computer, however processors aren’t without their drawbacks — or at least things that you need to consider. For example, a processor generally generates a lot of heat. But there’s much more to it than that — it’s not just that processors generate heat, it’s that particular components react with heat a lot more than others.

The thermal parameters of a processor is an important thing to consider if you want to dive a little deeper into processors, how they work, and what they can handle. Here’s an outline of processor thermal parameters and what those parameters mean.

Ambient temperature

Ambient temperature is, as the name implies, the average temperature of the air surrounding the processor. Usually, the ambient temperature is measured at a specific distance from the processor itself, and in the lab it’s measured 12 inches from the processor. Ambient temperature is usually denoted by TA.

Case temperature

The case temperature also measures a temperature around the processor, but instead of air it measures the temperature of the case. Unlike ambient temperature, where there’s a specified distance away from the processor, case temperature is measured usually where the case is hottest. As Intel notes, special care has to be taken when measuring case temperature to not confuse it with ambient temperature, as the case can lose heat through radiation or conduction with other surfaces it comes in contact with. Case temperature is denoted by TC.

Junction temperature

Processors are made up of millions of tiny transistors which are all interconnected by metal parts. Together, that’s called the processor’s die — and the die’s temperature is what “junction temperature” is. Junction temperature is higher than the ambient or case temperature, since normally it’s what raises the ambient and case temperature in the first place. Junction temperature is dictated by TJ.

Thermal resistance

The fourth and final thermal parameter on a processor is the thermal resistance, and is basically a measure of the processors ability to resist heat along the heat flow path and between the silicon die and the processor’s exterior. Thermal resistance largely depends on the processors material, the geometry of the processor, and where the processor is located in your computer’s case. Thermal resistance also depends on the computer’s cooling configurations and the location of the heat sink.

Thermal design power

Thermal design power, also known as TDP, is the amount of power that a processor dissipates to prevent overheating. What does that mean? Well, for example, a 12W TDP part will need a small fan or even just a passive heatsink to be cooled, while a 95W TDP part would need a dedicated heatsink or a larger fan. TDP is most often attached the spec sheet of a CPU or GPU, however it’s not limited to the processor — or even computer parts.

It’s important to note that thermal design power does not equal power consumption, even though the two are both measured in watts. If you’re building a computer, keeping TDP in mind is important — not for the sake of your power unit, but for the sake of your computer’s cooling.


The processor is a complex part of the computer, and how a processor handles heat is just one aspect of a processor in general. Hopefully, however, this guide will give you a somewhat deeper understanding of processors.

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