Summary
You can buy a laptop with anRTX 4090 GPUin it, but is itreallya 4090? It has the same name as NVIDIA’s desktop monster, but this and virtually all laptop GPUs are not what their names suggest.
Laptop and Desktop GPUs Share Names and Nothing Else
GPU (graphics processing unit)makers have been confusing customers with their naming choices for years if not decades at this point. With the 30- and 40- series laptop GPUs, NVIDIA is perhaps the biggest offender here, since there is no difference at all in the naming scheme of their laptop GPUs and desktop GPUs. A laptop RTX 3070 Ti for example, is closer to a desktop 3060 Ti in performance, and, while impressive, the RTX 4090 laptop GPU performs like a desktop RTX 3090.
In rare cases, such as with the RTX 4060, the laptop and desktop graphics cards are, in fact, the exact same chip. But in the vast majority of cases the two GPU share nothing except for their names. When it comes to AMD, its naming scheme still goes to the trouble of adding an “M” to the end of its mobile GPU name. Still, that won’t help you understand the real difference between, for example, a Radeon 6800M and 6800. So if you really want to suss out what sort of performance you may expect from your prospective laptop purchase, here are a few things you can do.
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Look Up the Architecture
The “architecture” of a GPU is essentially its technological generation. All GPUs running on the same architecture share features, efficiencies, and relative performance. With current laptop GPUs, the architecture of these mobile chips is the same as that of their desktop counterparts, but this wasn’t always the case and it’s possible that it may one day again be that architectural differences exist between desktop and laptop GPUs.
Either way, you may easily look up the GPU architecture of any GPU using Google. Sites such asTechPowerUpmaintain a database of GPU specifications, and so you can double-check that the laptop GPU you’re considering uses the same architecture as its desktop namesake. You can also use utilities likeGPU-Zif you already have the laptop in your possession.
Examine the Specs
The next thing to do islook up the specificationsof the GPUs in question and compare them. There are a few key specs to look out for:
Looking up these key specs can give you a good idea of what desktop GPU your laptop GPU is most like. For example, the RTX 4060 has an identical GPU for both laptop and desktop variants, but the desktop model has better, faster memory, leading to a small bump in memory bandwidth.
Comparing the desktop RTX 4080 to the laptop RTX 4090 shows that they have identical shader unit, ROP, and TMU counts. In other words, the laptop 4090 is a desktop 4080, but running with less total power and clock speed. Speaker of total power, that brings us to the next most important issue.
Determine the TDP
TDP orThermal Design Poweris how much power a given GPU is designed to use and then dissipate throughcooling. All things being equal, the more power a GPU can use, the better it will perform. Laptops are thermally constrained, so the same GPU in different laptops will have different power limits. An RTX 4060 with a 45W TDP will perform much worse than the same GPU with a 100W TDP.
This is another area where laptop makers can confuse customers. With varying TDP ranges, lower-tier GPUs can outperform higher-tier GPUs with better power limits, or two laptops with the same GPU can perform very differently. This is why you need to look up the TDP for your specific laptop GPU as it’s implemented in a specific laptop. In general you want a laptop GPU that’s at or close to the maximum TDP for that chip, unless you value slimness and portability over performance.
While it may take some digging, manufacturer’s do list the TDP figures for their GPUs, or alternatively you can search for independent reviews of the laptop which will usually list the TDP of the chip.
Compare Benchmarks
Laptops are complete systems, and so focusing just on the GPU in isolation is of limited usefulness. Whether you want a fast GPU for gaming, work, or both, the best way to judge a GPU is through actual performance measurement. This means you need to look up benchmarks for the laptops you’re interested in buying to see how they perform in the games and applications you want to use. This will let you know how that specific laptop performs with that particular combination of components and cooling performance. Because no matter what specifications a GPU (or entire computer) has on paper, it means nothing in the face of actual real-world performance.
Now, hopefully, you’ll be spared from buying a shiny new gaming laptop with very inaccurate ideas of how well it will perform based on the arbitrary names the GPU makers have decided to use.
