What is the TDP, what is it for and how is it calculated?

Normally, we talk about the TDP of processors and graphics cards, even the TDP that a cooler can dissipate, but what is the TDP and what does it refer to? In this article we want to explain what TDP or Thermal Design Power is. Although it is measured in watts (W), it does not refer to electrical watts, but to thermal watts, which is how it is measured in the case of electronic components, the heat that they are capable of generating or dissipating. Here we will explain, how it is calculated, what we should know about it and the reason for its importance.

How to calculate the TDP

Here we must take into account several points. The first is the maximum temperature that the processor can reach, the ambient temperature of a room and the minimum temperature per watt that must be dissipated. These three factors will give us the TDP, not only of the processor or the GPU, but also the TDP that a heatsink can dissipate, be it active or passive.

Parameters for your calculation

TDP (Watts) = (tCase (° C) - tAmbient (° C)) / (HSF Θca)

• tCase(°C): It is the maximum temperature that can occur between the internal union of the IHS and the DIE of the processor, to reach nominal performance. It refers to the heat transfer between the silicon and its metallic coating. The better the heat conductor, the better the heat transfer efficiency and the better heat can be dissipated.
• tAmbient(°C): This parameter tells us the maximum ambient temperature that must be given for the heatsink fan to offer nominal performance. Come on, so that we understand, it is an ambient temperature that is usually unfavorable, so that we do not have any scares.
• HSF-Θca (°C/W): This last parameter is the minimum temperature value for each watt in the heatsink, for the processor to work at nominal performance. The better this factor (higher), the lower the TDP and the smaller the heatsink required.

Practical example of calculating the TDP of a CPU

This is the theory, but how is it calculated in practice? For this example, we have used the AMD Ryzen 7 1800X, which has a TDP of 95W.

• tCase (° C): The maximum temperature established by AMD for this processor is 89.2ºC.
• tAmbient (° C): This temperature value, established by AMD, is 42ºC
• HSF-Θca (° C / W): AMD sets a value of 0.4972Θca, for the performance of a heatsink, so that the processor can function optimally. Most heatsinks on the market exceed this value, without problems.

TDP = (89.2 - 42) /0.4972 »TDP = 94.93W

What is the use of TDP in computing?

Now we know how the TDP is calculated in processors, graphics cards and so on. Now it's time to know the importance of this value. This value establishes that the processor, if necessary, can offer full performance or what is the same, as long as the processor is below the maximum temperature established by the manufacturer, it can perform at its best. Temperature is so important that Intel and AMD processors are designed so that, if the maximum supported temperature is reached, to avoid damaging the processor, the working frequency is lowered, to help cooling.

This is why there is normally a lot of emphasis on the need for a good heatsink, capable of keeping the temperature at bay. If the heatsink is very good and keeps the temperature stable, even though the processor reaches the maximum working frequency, there is nothing to fear, it will work perfectly and you will be able to work for a longer time at the maximum.

Conclusion

The importance of the TDP or thermal watts is very important and must be taken into account. A low-quality heatsink and low TDP, can cause problems in terms of performance, since if the value of thermal watts is equal to or lower TDP than the processor, it will work below its maximum possible performance, since the thermal limitation of the processor, it will prevent that of more of itself, if you notice an excess of temperature.

Many times it is spoken of excess of heatsink. If we talk about a 140W for a 65W processor, it may be in excess, but we will never have temperature problems, what's more, the processor is at a better temperature and will extend the life of the processor. Hopefully you liked it and it helped you.