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

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Robert Sole Follow on Twitter Send an email 4 April 2018

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

Table of Contents

How to calculate the TDP

Here we must take into account several points. The first is the maximum temperature 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 the TDP that a cooler can dissipate.

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 junction of the IHS and the DIE of the processor, to achieve the nominal performance. It refers to the transfer of heat between silicon and its metallic coating. The better the heat conductor, the better the heat transfer efficiency and the better the heat can be dissipated.
  • tAmbient (° C): This parameter indicates 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 value of temperature for each watt in the heatsink, so that the processor works at nominal performance. The better this factor (higher), the lower the TDP and the lower heatsink will be required.

Practical example

This is 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

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.


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.

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The 5 Best Online Power Supply Calculators

Whether you’re buying a new power supply, or are just curious about how much electricity your PC uses, an online power supply calculator can help.

These handy web tools work out the combined power requirements of your components, so you can make an informed decision about the wattage you need. Here are some of the best power supply calculators around.

Why Use an Online Power Supply Calculator?

Every component you add to a PC will draw electricity from the power supply unit (PSU). The more you add, the more power you need. RAM, graphics cards, processors, motherboards—they all need juice to run effectively and safely. This only increases if you start overclocking your components.

If your PSU is too weak to power all your components, you can quickly run into problems. Your PC may not start, it could suffer seemingly random shutdowns, and your operating system could freeze. If you’re particularly unlucky, it might burn out, taking your motherboard and components with it.

Online power supply calculators can help you avoid such issues. They’re not 100 percent accurate, but they can indicate if your power supply is obviously insufficient or running at close to capacity. It’s important to remember, however, there are other factors you should consider when choosing a PSU. Cheap PSUs often supply less power than they claim and may be less reliable.

The main focus of the Extreme OuterVision website is the PSU calculator, but it also provides power supply reviews and example builds for different purposes. The power supply calculator can be set to either Basic or Expert.

Like other PSU calculators, you choose your components using a variety of dropdown menus, sliders, and text boxes. The Expert version expands the number of these to include advanced settings, like overclocking and liquid cooling.

In either case, you can set how long your PC will run every day, and how much of that time will be spent on high-demand tasks like gaming or 3D rendering. In both modes, you can only set the motherboard option to Server, Desktop, or Mini-ITX.

Most of the fields only allow for generic components, like 8GB DDR4 RAM or 256GB SATA SSD. However, you can choose specific processors and graphics cards, which presumably means more accurate results. This is the only calculator in this list that includes monitors.

The results include load wattage and recommended wattage. In Expert mode, you can also see combined amperage and an estimate of your energy costs. The OuterVision site also features a power consumption calculator for cryptocurrency mining rigs.

As well as working out the potential mining profitability of your rig, it links to Amazon, where you can buy the parts to build it.

Most tech enthusiasts know Cooler Master. It makes a wide range of cases, coolers, power supplies, and peripherals for PC builders.

If you’re building a straightforward PC without a lot of extra bells and whistles, Cooler Master’s PSU calculator can give you a reasonable estimate of your power requirements.

It offers a choice of seven motherboard form factors, including ATX and Mini-ATX, but not specific board models. You can set your particular processor and graphics card too, but everything else is generic.

It doesn’t offer anywhere near as many options as the OuterVision calculator, but it does cover the basics well enough. And, of course, this calculator exists as a way to recommend Cooler Master power supplies. Cooler Master is widely considered a trusted and reliable brand for PSUs, but it’s important to recognize that bias.

Like Cooler Master, Be Quiet makes cases, PSUs, fans, and other PC parts, so its calculator naturally recommends its own products. Its PSU calculator is similarly stripped-back, but it has some interesting options that make it worth a look.

As with other calculators, the only areas you can fill with specific models are for the processor and graphics card. It doesn’t have options for the motherboard at all, and you can only specify a quantity of SATA disks, PATA disks, and RAM sticks—not their speed or capacity.

It also has some simple overclocking options (overclocked or heavily overclocked), as well as a setting for USB 3.2 power transmission. But what stands out is the ability to save configurations to your PC as text files. This may not be that useful with such a relatively simple calculator, but it’s nice to have the option.

Once you’ve made a calculation, the site will offer you a selection of Be Quiet power supplies, with options to filter the results further.

This PSU calculator is best for older computers, since it doesn’t appear to have been updated for a while. It’s missing a lot of newer components, but it also allows you to add FireWire connections to your specification, which you may not find with new calculators.

Also worth noting is the bar chart it produces at the end. This shows you the distribution of power throughout your system, both when idling and when under load. This isn’t something most other calculators offer.

Along with usual components like hard drives and SSDs, you can add peripherals such as keyboards and mice. You can also include a variety of PCI and PCI Express cards, and up to five fans. There are some overclocking sliders for processors too.

If you have an older PC and want to check its energy consumption or replace its PSU, this calculator is worth trying. It offers some interesting results you won’t find anywhere else, and it doesn’t push you to buy anything. For new PCs, though, you will need to use one of the other calculators.

PCPartPicker presents you with a list of all the essential components you need to build a PC. Under each heading is a button, which you click to add a part. You then get a long list of actual products to choose from, including prices from various merchants.

As you add parts to your list, the System Builder keeps track of the compatibility of your components and the overall estimated wattage. You also have the option of exporting your list. The site automatically generates a unique link you can share, but you can also generate markup text that you can copy and paste to embed elsewhere.

Your lists can also be saved to your account if you create one. Plus, you can see a history of all the lists you’ve made, which is perfect if you want to compare potential builds.

It’s not a dedicated PSU calculator, so it doesn’t give you a breakdown of energy requirements, and doesn’t take overclocking into account. But it does allow you to choose actual components for every part of your build and then base the PSU requirements on that.

How Accurate Are Power Supply Calculators?

PSU calculators can only give an estimate, rather than an exact figure. Therefore, you can use them as a guide, but don’t take the results as gospel.

In our tests, we imagined a gaming PC with a high-end graphics card and processor, 16GB of DDR4, a SATA SSD, and a 7200rpm hard drive. The recommendations we got from the calculators ranged from 527W to 580W.

In all cases, those figures were lower than expected. Nvidia, for example, states a high-end card like the GeForce RTX 3080 requires at least a 750W PSU.

Get the Right Amount of Power to Your Rig

Indeed, it’s best to have some overhead when choosing a power supply, so whatever these calculators suggest, you should probably add a couple of hundred watts on top. They seem to all be guilty of suggesting the bare minimum.

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CPU TDP and how it is calculated in Intel and AMD

Home » Computer for beginners » What is CPU TDP and how is it calculated in Intel and AMD


  1. What does CPU TDP mean?
  2. What is the difference between the TDP of an Intel and AMD processor?
  3. The formula for calculating the TDP of the Processor itself is as follows:

Most users believe that they know what TDP of the processor is. However, in reality, the situation associated with this function is much more complicated and confusing than it might seem at first glance. We decided to write an article to clarify once and for all, which means the TDP of the processor and how it is calculated in Intel and AMD .

What does the processor TDP mean?

The value of TDP is Thermal Design Power ( Thermal Design Power ). This value indicates the maximum amount of heat that the CPU or GPU can generate under average use. The TDP value of is expressed in watts and is used as a guide to determine the amount of cooling needed to prevent components from overheating.

A small fan is enough to cool a Raspberry Pi 4 with a low power processor.

For example, a low power processor with TDP 12 W can be cooled with a small fan or a single heatsink. On the other hand, a processor with a TDP of 95W will require a fairly large heatsink with a good fan. Moreover, many users compare this figure with the actual power consumption of the components. But this is fundamentally not true.

Since this figure is based on thermal characteristics, one can only guess how much energy a particular component consumes. Low TDP usually means lower power consumption. This results in less heat generation and longer battery life. However, TDP does not indicate maximum power consumption. Rather, it is a nominal value that can serve as a guideline.

In addition, each manufacturer conducts its own internal tests and calculates the TDP value of its equipment. Therefore, comparing the TDP of different manufacturers is not entirely correct. Also, different chips have different maximum temperatures. For example, the critical temperature can be 100 degrees or 40 degrees. And since TDP reflects the requirements of the cooling system, the value will be higher in the latter case. Because the chip needs more active cooling and therefore requires a cooler that can dissipate more heat.

What is the difference between the TDP of an Intel processor and an AMD processor?

Intel Core i9-10900K

Processor Specifications Manufacturers are responsible for specifying the exact TDP of their components, the approach of Intel and AMD is somewhat different. The Intel processors have three main specifications: advertised TDP, base frequency, and Turbo Boost frequency. For example, the Core i9 -10900K processor has a base frequency of 3.7 GHz and a maximum frequency of Turbo Boost 5.3GHz @ TDP 125W .

However, the Intel claims that this TDP is only guaranteed when the processor is running at a base frequency of 3.7 GHz for all cores. As soon as the processor reaches higher frequencies, its TDP also increases. However, the TDP requirements for these cases are not fixed.

For other processor models, the difference between the base and turbo frequencies may be much smaller. But it can be so large that your cooling system is rated at TDP will start to fail. Especially when working at higher frequencies for a long period of time. Therefore, when buying a powerful processor, you should carefully choose a cooling system.

Original AMD rep post on Reddit

On the other hand, many users believe that the TDP of the AMD processors is «more correct», although the company actually calculates it a little differently. Thanks to the message from the representative AMD on Reddit , we now know what formula the company uses to calculate the TDP of of its processors. At the same time, the message makes several important claims about this formula:

  • TDP refers to heat, not electricity.
  • TDP is the final value given to cooler manufacturers. What thermal resistance is acceptable for the cooler to achieve the processor performance specified by the manufacturer.
  • The thermal resistance of radiators is measured in units of θca (the first character is the Greek letter Theta), which stands for degrees Celsius per watt.
  • In particular, θca is the thermal resistance between the processor heatsink and the environment.
The formula for calculating the TDP of the Processor itself is as follows:

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

tAse for connecting a glass dome/distributor to reach the rated power.

tEnvironment°C: Optimal CPU fan inlet temperature to reach rated power.

HSF ϴca(°C/W): minimum heat sink resistance in degrees Celsius per watt required to reach rated power.

An example is TDP calculation for AMD Ryzen Threadripper1950X processor:

(56° - 32°)/0.133 = 180W TDP.

Here, 0.133 ϴca is AMD’s target for cooler thermal performance at which the processor’s rated power can be reached.

In other words, for the Threadripper 1950X , the company suggests an optimum temperature of 56°. And recommends a cooler with a thermal resistance of 0.133 ϴca to achieve the specified performance. Therefore, power consumption is not included in the TDP calculation at all.

When choosing a processor, look at the different approaches companies use to calculate TDP. Also try to choose the right cooling solution.

What is the TDP of a processor and can it be changed

The characteristics of component devices may include various parameters, often incomprehensible to the user. So, when choosing a processor, video card or cooling system, you can notice such a value as TDP, related to thermal characteristics and expressed in watts. Let’s consider what this parameter reflects, why the owner of the computer may need it and how to determine it, and whether its value can be influenced.

What does TDP mean? The decoding of the parameter sounds like Thermal Design Power, which means “calculated thermal power”.

The value indicates the maximum amount of heat generated by the chip during operation (assuming average load values), the same heat must be removed by the cooling system. Thus, the parameter indicates the design requirements for heat dissipation and can be used to determine the required specifications, for example, when choosing a suitable cooler.

The value is expressed in watts, which introduces confusion in the values ​​and causes TDP to be equated with power consumption. Although the connection between these concepts can be traced, the manufacturer, when indicating TDP, meant a slightly different message, since the value is related not to electrical, but to thermal watts. Thus, in the case of TDP, we are not talking about electrical power, the parameter is abstract and is used by Intel and AMD to indicate information about the heat dissipation of processors and video cards. Taking into account the characteristics, it is recommended to select cooling for the correct operation of the device.

Interpretation of the parameter by manufacturers

At the same time, different manufacturers can calculate and interpret TDP in different ways (the value is calculated by formulas during the operation of the device under certain loads and conditions), which should also be taken into account. Thus, the declared TDP cannot reflect power consumption and performance, and the value is not used to compare these parameters, in particular, when it comes to devices of different architectures and manufacturers.

For modern Intel processors, this concept refers to the heat in watts that the CPU releases during prolonged operation at the base frequency. But there is also a Turbo Boost mode, and when higher frequencies are reached, the TDP also increases, that is, even with a slight difference between the base and Turbo, the cooling system, which is designed for the nominal TDP, may not be able to cope with its task. Thus, the actual heat generated and power consumption may increase above the specified TDP parameter, which indicates that for Intel products this value will be lower than the maximum power consumption and dissipation.

AMD has a completely different picture. Here, the declared TDP characteristics of the CPU and GPU are already closer to the real indicators of the maximum allocated and consumed power during normal operation.

IMPORTANT. In view of the foregoing, it should be understood that buying a processor with a value declared by the manufacturer, for example, TDP 95 W and a cooling system with exactly the same parameter, does not guarantee that the device will not be subject to overheating under the specific conditions in which you operate the computer.

As for NVIDIA, the manufacturer equates power consumption and power dissipation, defining the TDP parameter as the maximum power consumed by the system during operation, and the maximum amount of heat that the cooling system needs to remove.

Why you need to know the TDP of the processor

When assembling a computer or upgrading it yourself, as well as overclocking the system, the process should be approached with all responsibility and many factors should be taken into account so that in the end all components are compatible with each other and work smoothly. Information about the calculated thermal power of the processor is useful to the owner of the computer and can be used:

  • when choosing the most suitable cooling system option — a similar parameter is also stated in the specifications. Thus, the value of dissipated heat for the efficiency of heat dissipation, and, accordingly, for maintaining a normal temperature and proper operation of the device, must correspond to TDP (at least) or be higher than the heat dissipation of the processor. It is better if the cooling system is purchased with a margin of 50% of the declared TDP, and when planning overclocking, you should impose even more stringent requirements on cooling, since the cooler will have to remove heat much more. When choosing a cooling system, you need to pay attention to such a parameter as a socket on the motherboard;
  • when choosing a power supply that is suitable for its power characteristics, selected taking into account the parameters of those components that are already installed or planned to be installed. It should also be taken into account here that Intel’s peak power consumption can even double the TDP declared in the technical documentation.

The power consumption and performance of processors with the same TDP may vary. Most often, heat dissipation requirements are stated not for a specific model, but for a whole family of processors, while the cooling system will need less heat dissipation in the case of younger models. The specified frequencies do not affect the parameter declared in the characteristics, there are many options for devices with different frequencies, but the same TDP. At the same time, the dependence of power consumption on frequency is non-linear; an increase in clock frequencies above a certain threshold will also require an increase in the supply voltage. With overclocking, the heat dissipation becomes higher than in normal mode, and the TDP parameter loses its relevance, while the cooling system should be even more powerful.

Determining the TDP of a processor

Although TDP is an abstract value that does not determine the actual heat dissipation of a processor, it also serves as a guideline when choosing a cooling system or power supply. In the main characteristics of the device, the parameter is not specified by the manufacturer, and therefore many are wondering how to find out the TDP.

There are several ways to find out this information:

  • Processor heat dissipation information is available in advanced specifications, namely in the thermal characteristics section of the product card in any store;
  • TDP can also be determined by the device model by searching for the specification on the manufacturer’s website;
  • Another way is to use special utilities such as CPU-Z, AIDA64, Sandra.

Can TDP be changed? In practice, TDP limits make identical chips different. It can be either a thin ultrabook or a desktop PC, and, of course, they have different heat dissipation requirements — for example, 65 watts for a laptop will be a lot, but for a computer it is considered acceptable.

In the case of CPU or GPU laptops, reducing the indicator improves battery life and reduces heat, while performance will be lower, since the frequencies are reset under prolonged load, although in the case of resource-intensive, but fast tasks, there will be practically no difference in performance . Such a decision is usually associated with the rest of the device, when the installed cooling system is not able to effectively cool the device with the specified characteristics. That is, for example, the processor has a TDP of 15 W, while the maximum value of the same chip can reach 25 W, and if such a configuration is used with the same processor, it will be more productive. In the first case, if we compare two devices, we can count on a greater autonomy of the device (with the same battery capacity) and low heating.

The TDP value is adjusted in various ways, and not only the manufacturer, but also the user himself can increase or decrease this parameter. Most often, the value is adjusted by software by manipulating the processor clock frequency and voltage, which is performed through the BIOS settings or through special utilities. So, you can reduce the heating (and at the same time the amount of power consumed and performance) if you reduce the TDP, while controlling the stability of the device so that the procedure is safe.

Some motherboards offer the ability to manually change the TDP limit, which does not deprive the processor of the use of automatic overclocking technology, but only reduces the limits in which it will be performed. In the BIOS settings, for this you need to find the cTDP parameter, most often it is located in the Advanced tab (the location of the option may differ depending on the motherboard).