A CPU falling into blue water.
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You often see TDP measurements on specification sheets, and it’s important info for people with desktop PCs. But TDP definitions are like opinions—everybody’s got one. Let’s cut through the confusion and talk about what a TDP number means for you.

What Does TDP Mean?

TDP is an acronym people use to refer to all of the following: Thermal Design Power, Thermal Design Point, and Thermal Design Parameter. Luckily, these all mean the same thing. The most common is Thermal Design Power, so that’s what we’ll use here.

Thermal Design Power is a measurement of the maximum amount of heat a CPU or GPU generates under an intense workload.

Components generate heat as a computer works, and the harder it works, the hotter it gets. It’s the same with your phone. Play a game like Brawl Stars for about 30 minutes, and you’ll notice the back of your phone gets hotter as the components use more electricity.

Some PC enthusiasts also refer to TDP as the maximum amount of power a component can use. And some companies, like NVIDIA, say it’s both:

“TDP is the maximum power that a subsystem is allowed to draw for a ‘real world’ application, and also the maximum amount of heat generated by the component that the cooling system can dissipate under real-world conditions.”

Most of the time, however, TDP means the amount of heat a component generates and a cooling system must remove. It’s expressed in watts, which is usually a measure of power (like electricity) but can also refer to heat.

TDP is often used as a stand-in for power draw because the two often end up being equivalent or close. That’s not always the case, however, which is why you shouldn’t use TDP to decide the size of your PC’s power supply.

TDPs for Processors

A water cooling system inside a desktop PC.
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AMD vs. Intel

If TDP is based on the amount of heat generated during a heavy workload, who decides what that workload is, or at what clock speed the chip should be running? Since there’s no standardized method to rate TDP, chip manufacturers come up with their own methods. That means PC enthusiasts have vastly different opinions about TDPs for Advanced Micro Devices (AMD) versus Intel CPUs.

In general, enthusiasts argue that AMD’s TDP numbers are more realistic. Intel, meanwhile, often publishes TDP ratings that are lower than what people experience with their systems, which makes TDP less reliable as a stand-in for power draw.

Anandtech recently explained how Intel arrives at its TDP ratings, and why they always seem to be off. CPUs operate at their boost levels (faster speeds) when under heavy workloads for sustained periods of time. The trouble is Intel bases its TDP ratings on when the processor runs at the base frequency rather than boost. So, an Intel processor frequently runs hotter than what Intel says you can expect on the box. If the system’s cooler can’t deal with those higher heat levels, the processor slows down to protect itself from damage. This results in poorer system performance. With a better cooler, though, these problems are less likely to occur.

Meanwhile, on the AMD side, there are many forum posts in which people argue that even with moderate overclocking, AMD’s stock coolers are more than adequate.

It’s All About Cooling

A CPU cooler with large fan and copper pipes protruding from the bottom.
Cooler Master

You can manage your system’s TDP if you use the best cooling solution for its CPU. If you don’t do any specialized tweaking to your system or prolonged AAA gaming, the stock cooler that comes with your CPU should be fine. Gamers, however, should look around—especially if you play games that rely heavily on the processor.

An aftermarket cooler can most likely deal with any heat your CPU throws at it. This web page lists more than 60 coolers from Cooler Master, a well-known PC equipment manufacturer. More than half of them have TDP ratings of 150 watts or higher, which should be enough for most consumer-grade CPUs. You can find CPU coolers at all sorts of price points. There are liquid cooling solutions that cost hundreds of dollars, and capable 150-watt heatsink and fan coolers for $20 to $50.

A proper cooler is only part of your PC’s heat-removal system. Proper airflow is also key. Be sure to check out our primer on how to manage your PC’s fans for optimal airflow and cooling.

TDP, T-Junction, and Max Temps

TDP helps you choose the right kind of cooling system for your CPU. What it doesn’t tell you, however, is how much heat a component can safely tolerate. For that, you need to look at one of two things.

If you have an Intel processor, you need to check the T-junction. Intel says it’s the “maximum temperature allowed at the processor die.” The “die” refers to the tiny areas of circuitry on a silicon wafer. For example, for the Core i9-9900K, the TDP is 95 watts, and the T-junction is 100 degrees Celsius. To find the T-junction for your CPU, go to Intel’s Ark site and look up your processor model.

AMD, meanwhile, uses the more straightforward term “Max Temps.” The Ryzen 5 3600 has a TDP of 65 watts, the Ryzen 5 3600X has a TDP of 95 watts, and both have a Max Temps of 95 degrees Celsius.

These are good numbers to know if you need to troubleshoot a PC that gets too hot. Overall, however, it’s best to focus on TDP first.

Graphics Cards

AMD's Radeon RX 5700 XT.
AMD’s Radeon RX 5700 XT graphics card.

For mainstream consumers, TDP is more important for CPUs. Graphics cards have TDPs, but they also include built-in cooling solutions. You can get aftermarket GPU coolers, but they’re more difficult to install and generally unnecessary unless you’re into heavy overclocking. If you want to know your graphics card’s TDP, TechPowerUP is a reliable source.

Thermal design power is an important specification, especially for CPUs. But don’t get confused about its meaning. TDP helps you pick the right cooling solution for your components. And that’s it.

Ian Paul Ian Paul
Ian Paul is a freelance writer with over a decade of experiencing writing about tech. In addition to writing for How-To Geek, he regularly contributes to PCWorld as a critic, feature writer, reporter, deal hunter, and columnist. His work has also appeared online at The Washington Post, ABC News, MSNBC, Reuters, Macworld, Yahoo Tech, Tech.co, TechHive, The Huffington Post, and Lifewire. His articles are regularly syndicated across numerous IDG sites including CIO, Computerworld, GameStar, Macworld UK, Tech Advisor, and TechConnect.
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