In This Article
What is Thermal Design Power (TDP)?
TDP or Thermal Design Power refers to a specific number represented in watts usually. It represents the maximum amount of heat generated by a CPU.
From the technical point of view, the TDP is the basic indicator of power consumed by the CPU and also indicates the amount of heat the cooling system needs to dissipate from the CPU.
In simple words, TDP is the thermal profile of a CPU and the thermal requirements for its allied products.
KEY TAKEAWAYS
- The TDP indicates the heat generated by the CPU and higher the TDP, more cooling will be required.
- TDP can vary in a laptop CPU and a desktop CPU and from one component to another depending on several factors such as number of cores and memory cache.
- TDP is very important because it tells about the power consumption and cooling requirements of the CPU but it alone does not affect its performance.
- TDP is calculated on the basis of the workload and clock speed but there is no universal method for it which is why the TDP rating of one manufacturer may be different from the other.
Understanding Thermal Design Power (TDP) in Processor
Thermal Design Power refers to that number in watts that indicates the maximum heat of the chip.
It can be a CPU chip or a GPU chip. In simple terms, TDP of a processor is considered to be the fundamental indicator of power utilization.
Commonly, it is believed that more watts mean better performance.
Though it is true in some parts, it also means that higher temperatures equals more power consumption.
Therefore, the manufacturers of computer processors sometimes lower the TDP on a CPU, especially those that are designed to be used in the laptop computers and other mobile devices, simply to increase the battery life and the speed of performance.
Since it is all related to heat and temperature, when you shop for a CPU you should ideally check the TDP in particular.
This will give you a fair idea about the type of cooling system you need in order to keep the system cool as well as ensure that the Power Supply Unit or PSU continues to provide enough juice to it.
The published TDP value by the OEMs will therefore tell you about the power requirements of the processor as well as the thermal solution capacity.
You can check this value on an Intel processor by:
- Visiting their official product specification site, ark.intel.com
- Entering the product number of your processor and
- Clicking on ‘Performance.’
The TDP value will be displayed there.
For example, if it shows that your CPU comes with a TDP of 90 watts, you can expect it to generate 90 watts of heat while it is in operation.
However, keep in mind that this TDP value is not fully accurate and it is not completely wrong either.
The 90 watt CPU in the example will not need 90 watts of power from the supply.
It is highly unlikely that your CPU will hit that 90 watt TDP mark unless you use extremely intensive processes and applications on your computer.
Even though the unit ‘watts’ signifies so, actually it does not refer to the raw power input required by the component.
Instead, the Original Equipment Manufacturers use this value as the nominal value for designing the cooling systems.
The higher the value of the TDP, the more cooling will be needed and it can be in any form such as:
- Liquid platforms
- Traditional fan based coolers or
- In any passive technologies.
Therefore, TDP does not necessarily mean the total power drawn by the component but that surely does not mean you cannot use that value as an estimate.
This is because this value is itself based on power.
However, the values provided by the manufacturers also vary quite significantly because these are based on the findings of the respective manufacturers.
Therefore, do not consider the value to be written on stone and design a cooling system around it.
Instead, consider this as a rough idea about the amount of output the PSU will need to have.
If all this information regarding TDP has still left you bowled over, the following information will surely be more helpful.
Dennard Scaling
According to Dennard scaling, a circuitry becomes more efficient as it becomes smaller.
This means that it will consume less power while offering higher performance.
It is for this reason the CPUs that are made up with a smaller process node, and consequently smaller transistors, are usually considered to be much more powerful in comparison to those processors that come with a higher TDP.
This indicates that the processors that belong to the same generation and those that have a higher frequency usually consume more power and at the same time come with a higher TDP.
There are different factors that affect the amount of power used by a CPU such as:
- The number of cores
- The size of the onboard memory cache and more.
However, TDP of the CPUs alone typically and necessarily does not show a relationship to their performance.
That is why, as a rule of thumb, it is believed that a processor that comes with a higher Thermal Design Power than another CPU can be either less efficient, more powerful, or both.
Importance
TDP is quite an important value to consider especially if you are building a computer system.
This is because there are two most important factors that you should keep in mind while building your system which are:
- Power consumption and
- Cooling requirement.
This means that the PSU must provide sufficient power to all the parts of the computer system and the heat that will be generated inside the system during operation also needs to be removed efficiently.
And, to both these aspects, the TDP of the processor is the most significant indicator.
That is why you should look for the TDP. This will tell you about the amount of heat that is to be dissipated by the cooler on a chip when it runs a typical workload.
However, the TDP will not tell you the amount of heat that is dissipated by the chip itself when it runs at full load.
That is why you should always require having a cooling solution that is powerful and efficient enough to handle even much more heat than that is rated for the CPU, GPU, Soc, and others.
Once again, remember that the TDP refers to heat and not power.
Therefore, you will just get an idea from the TDP value about the amount of power the system may need or consume.
This is important because heat is actually a byproduct of the electricity consumed.
Therefore, a CPU with a high TDP will generate a lot of heat and usually the power draw of a CPU is normally higher than the TDP rated.
This means that, if a CPU is rated 65 TDP, it may draw 80 or 90 watts of power.
However, the amount of power actually consumed by a CPU depends on a few specific factors such as:
- The configuration of the CPU itself on a specific system
- The settings of the power limit
- The boost durations and more.
Moreover, there are several processors available in the market now that come with ‘overbuilt’ cooling features.
This allows boosting the CPUs for a longer time but still the thermals may not go out of control.
In such cases, the Thermal Design Power value may be absolutely pointless.
Rating TDPs for Processors
The amount of heat produced when a CPU runs at full workload is indicated by the TDP.
Now, there are two aspects of it such as:
- Determining the workload and
- The clock speed at which the CPU should be operating.
But, there is no universal method to estimate these values and therefore different manufacturers of CPUs follow different methods to estimate and rate the TDP of a CPU.
This means that there will be significant differences in the TPD values of the CPUs of Intel and the Advanced Micro Devices or AMD, two of the major manufacturers of CPUs today.
The users are also divided on this aspect.
While few users think that the TDP rating of AMD is much more realistic, there are other users who believe that it is the Intel CPUs that are more reliable in terms of TDP.
According to AnandTech, in reality, the TDPs of Intel CPUs are rated much lower than what the users actually experience.
The most significant reason for this deviation is that the Intel CPUs typically run at their boost speeds when they experience heavy workload for a persistent period of time.
However, the problem is that Intel rates the TDP of their CPUs based on the periods when the processors run at their base frequency and not at their boost frequency.
That is why the Intel CPUs often run hotter than what is said on the box.
If these high levels of heat are not properly managed by the cooler of the computer system then it results in slowing down of the processor in order to protect it from damages.
This means that your system will perform poorly. However, if the cooler is good enough then such issues are pretty less likely to come about.
On the other hand, as for the AMD CPUs there are several users who find their TDP rating to be much more accurate and the stock coolers are good enough to keep it cool as well.
What to Look for?
In order to know how much temperature the CPU can tolerate, the TDP of the chip will not be enough because it is more about the cooling aspect.
For that, you will need to look for different things depending on the brand of CPU in question. These are:
- T-Junction – If your processor comes from the house of Intel, you will have to check the T-junction. The value here indicates the maximum temperature that is permitted at the CPU die which is actually the minute area in the circuitry of a silicon wafer. The value mentioned here is expressed as degrees Celsius which may be higher than the TDP rating. You will need to go to the website ark.intel.com to find the specific T-junction for the particular processor model you want to buy or are currently using.
- Max Temp – This is where you should look for the maximum temperature tolerance of an AMD processor. Just as straightforward the term is, so are the values displayed here in degrees Celsius.
The maximum temperature tolerance of the CPU is a good thing to know because it will help you to troubleshoot your system when it gets very hot.
However, overall, it is always best to focus on the Thermal Design Power in the first place.
Compatibility with a Cooler
The TDP value is also very important to know because you will need to know about the compatibility of the CPU with the specific type of cooler.
Therefore, you should match the TDP of the cooler with that of the CPU and then choose one that exceeds the TDP of the CPU so that it can successfully prevent the processor from getting overheated.
It is needless to say that you should not use an 18 watt TDP cooler with a 225 watt Threadrripper if you do not want to roast steak on it because it will surely get as hot as a BBQ grill in no time.
However, when it comes to the compatibility aspect, it typically is based on the matched TDP and the physical compatibility.
This is because most of the Intel CPUs come with different rates of heat generation as well as mounting methods.
TDP Variance
Even if two CPUs have the same architecture, it may not always have a considerably higher TDP at higher clock speeds.
Since TDP is a specification of manufacturing, it is not a true measure of power consumed or heat produced.
Also, the CPUs are binned according to their respective manufacturing and temperature tolerances under normal operating conditions.
All chips are also not created equal and they are not identical which is why their TDPs vary.
Add to that, the silicon also affects the TDP rating because it may even alter the temperature tolerance of two similar CPUs.
Therefore, with all that said, TDP is to be considered as more of a manufacturing specification for the manufacturers of the CPU that is used to design the cooling systems.
That is all the TDP is.
Is Higher TDP Better?
Whether high TDP is good or bad is quite a legit question to ask but, sadly, the answer to it is not very simple.
In fact, to be on the safe side, it is neither good nor bad to have a higher TDP rating.
Why?
Well, to understand that, you will first have to understand what a higher TDP rating actually means and what effects it would have on the computer processor and its performance.
As said earlier, a CPU with a higher TDP rating will consume more power and also generate more heat.
Well, generating more heat does not mean it is very bad. It is just that you will need a better cooling system as well.
Also, a processor drawing more power due to higher TDP rating is not necessarily very bad. In fact, it is good on the contrary.
This is because when a CPU draws more power and also generates more heat it may also mean that it is faster and better in performance in comparison to those processors that come with a lower TDP rating.
Therefore, if you are looking for raw speed from your processor, then you should not stop from buying a CPU with a higher TDP rating.
And, on the other hand, if you are okay with a slightly lower performance and are more fascinated towards power efficiency you should go for a CPU with a lower TDP rating.
However, most of the newer processors, just like the video cards, usually come with a lower TDP rating but still offer more speed as compared to their older versions.
This is due to the fact that these are designed with newer technologies that allow the manufacturers of the chips to use smaller transistors while making them.
Being smaller in size, these newer transistors emit less heat and are also quite faster.
What Does 15W TDP Mean?
When you buy a processor with a TDP rating of 15 watts, it actually means that you will need a cooling system that can dissipate 15 watts of heat efficiently.
Therefore, as said earlier, the TDP value indicates the power of the cooling system required to keep the CPU cool and not the amount of heat it dissipates.
It also does not indicate the amount of power the CPU draws because a processor with a TDP rating of 15 watts can draw even 60 watts of electrical power depending on the workload.
Also, a processor with a TDP rating of 15 watts can have a higher idle power in comparison to a CPU with a higher TDP rating.
For example, the idle power of a CPU with 15 watt TDP can be 1 watt in one and 5 watt in another model while a CPU with a 60 watt TDP can consume only 2 watts of power in idle state.
It is for this reason C States were invented and used.
Is Lower TDP CPU Better?
If you use a CPU that comes with a lower TDP rating it is good because it will consume less power.
However, CPUs with lower TDP are usually the basic or low-end processors.
This means that the performance level of these processors will also be quite low.
On the other hand, if you use a CPU with a higher TDP it may consume more power and generate more heat but it will offer a much higher level of performance.
Therefore, a CPU with 65 watt TDP will consume less power and generate less heat as compared to a CPU with 95 watt TDP but it will come at the cost of much lower processing speed and level.
Does CPU TDP Affect Performance?
Yes, the TDP of the CPU surely affects its performance which is why you should be concerned about it when you buy a new processor.
When the TDP is higher it will translate to better and faster performance but at the cost of more power consumption and higher temperature.
On the other hand, when the TDP of a CPU is lower, it will consume less power and generate less heat but at the cost of its performance.
For example, if you consider two different CPUs of the same generation but with different TDPs of 15 watts and 60 watts, the one with a higher TDP will complete a given task in quick time.
On the other hand, the time taken by the one with a lower TDP to complete the same task will be higher since it will be much slower in performance.
Therefore, a CPU with a higher TDP rating will surely be much more efficient both in the terms of performance and consumption of energy.
This is because when you run a CPU, you use different other components as well such as the hard disk, a video adapter and the display of the computer.
The CPU with 60 watts TDP rating ensures better supply of power to all of them and hence the task is completed faster.
On the other hand, the 15 watt CPU will also need power to run the same additional components but when you look at the total amount of power consumed you will see that the CPU with a higher TDP rating is much more efficient in terms of electrical energy consumption.
However, the basic answer to your question would be – it depends on several factors such as:
- How much CPU intensive the task is
- The silicon quality of the CPU
- The manufacturing process of the cores
- The architecture of the CPU and
- The cooling system and its efficiency.
Finally, and most importantly, the power management settings of the CPU also play a significant role in determining the performance.
Does Less TDP Mean Less Heat?
There is no doubt that a CPU that comes with a lower TDP rating will consume much less power and thereby generate much less heat while in operation.
This is because a CPU does not perform any physical or chemical work. Therefore, all the electrical power consumed by the CPU eventually turns into heat.
That is why it is said that if you want to use a CPU with a higher TDP rating you should also use a much better cooling system.
The difference in temperatures of or heat generated by two CPUs with two different TDPs is typically based on two specific factors such as:
- The efficiency of the cooling system including the environmental temperature and chassis temperature and
- The amount of heat generated.
Therefore, lower the TDP, the better because lower will be the power consumption and thereby lower heat generated and lower cooling required. All these will have a direct effect on your monthly bill.
However, a CPU with a lower TDP rating may go down to the base clock state while running an intensive and multi-core workload over a long period of time.
This state is pretty low performing and therefore the CPU will compute less in comparison to a CPU with a higher TDP rating.
And, when you perform basic and low intensity tasks on your computer, it may also happen that two different CPUs, one with a lower TDP rating and one with a higher value, may consume the same amount of power and generate the same amount of heat.
Still, a processor with a lower TDP rating will consume less electricity from the power supply and generate less amount of heat.
Therefore, once again it can be said that everything depends on the specific tasks performed on the computer and the workload of the CPU.
Conclusion
So, coming to the end of this article, now you surely have much more knowledge about Thermal Design Power of a CPU than you had before reading this article.
With such knowledge now you will be able to decipher the technicalities behind it more easily.