Your laptop’s GPU often has a “TDP” or Thermal Design Power number buried in the specs, measured in watts. It’s easy to cover up, but TDP can be an important performance figure that you overlook at your peril.
What is TDP?
The Thermal Design Power (or sometimes Profile) is essentially the heat budget of a processor. It is designed to generate up to that amount and no more. TDP isn’t quite the same as the amount of power a processor like a GPU uses, but it’s in that margin.
What TDP is really all about is cooling. If a GPU has a TDP of 100W, it needs a cooling solution that can handle 100W of heat energy and remove it from the system quickly enough to avoid GPU throttling or even an emergency shutdown.
What does TDP mean in a laptop?
Laptops need to be energy efficient, all their components need to be squeezed into an incredibly cramped space, and they don’t have much room for cooling systems. This means that the cooling system that fits into a particular laptop chassis puts a limit on the TDP that the CPU or GPU can achieve.
The higher the TDP for a part, the faster it can work, the longer it can run under a heavy load, and the more power it can use to do it. In other words, if you have two 100% identical GPUs, but one has a TDP of 65W and the other 130W, there can be a huge difference between the two when it comes to performance.
The problem with GPU ratings of modern laptops
Knowing a laptop’s GPU TDP is now more important than ever. Why? It all has to do with how GPU makers, especially NVIDIA, name their mobile GPUs. In the past, you were given different names for the low-TDP and high-TDP variants of a GPU. For example, the GTX 1080 Max-Q performs about 10-15% slower than the regular model.
With the latest generation of NVIDIA GPUs, the difference in names has disappeared. Instead, each GPU can be set by the laptop manufacturer for a specific TDP. The RTX 3060 mobile GPU ranges from 80W to 115W with a total of eight TDP levels. The 80W card has a GPU clock range of 900-1425MHz and the 115W variant ranges from 1387-1702MHz. That’s a big difference in clock speed, with no clue in the name pointing to that difference.
The good news is that NVIDIA now requires TDP figures to be published in gaming laptop spec sheets. However, if you don’t know what the number means or if you need to pay attention to it, you’re not really better off.
Look at the benchmarks
The best way to approach buying a laptop with a modern GPU is to look at the laptop’s spec sheet and see what TDP that GPU is rated for, as well as the clock speed range. After that, you need to compare it to the range of possible TDPs for that GPU and see where in the stack your future GPU falls.
However, the important thing is to look for benchmarks between the different TDP levels for a particular GPU. If at all possible, you should find benchmarks for the specific laptop model you want to buy. Buying a high-performance laptop is a big investment, and you don’t want to find that your low-TDP variant isn’t up to what could have been a great performance.
Of course, if you prefer a cooler-running laptop with longer battery life, you might want the low-TDP variant of that film processor. Most importantly, you get the hardware you really wanted.