WHAT ABOUT LAPTOP GPUs?
All our testing has focused on desktop graphics cards. It allows us to test the various GPUs while keeping all other hardware constant, but there are also mobile variants of most graphics cards.
As you can guess, packing something like a 450W RTX 3090 Ti into a laptop just isn’t going to happen, not without drastically cutting the power use. That results in the latest mobile GPUs from Nvidia and AMD generally being at least one step down in performance from their desktop counterparts.
Take the mobile RTX 3080, for example. It uses the GA104 chip, whereas the desktop 3080 uses GA102. It also has 8GB of memory on a 256-bit bus instead of 10GB on a 320bit interface and comes with 48 SMs and 6144 CUDA cores compared to 68 SMs and 8704 CUDA cores. It typically runs at lower clocks as well. All those cuts are done to keep power consumption under control, and the resulting GPU can be configured to run at 80–150W, depending on the specific laptop and configuration, compared to the base 320W of the desktop 3080.
It’s a similar story for
AMD. The RX 6800M uses the smaller Navi 22 and has 40 CUs and 2560 shader cores, with 12GB of VRAM and
TGP (Total Graphics Power) starting at 145W. The desktop RX 6800 uses Navi 21 with 60 CUs, 3840 shaders, 16GB of memory, and a 250W TGP. The specifics of the various graphics chips over the years may vary, but the net result is the same: lower performance.
The 150W mobile RTX 3080, for example, comes close to the level of a desktop RTX 3070, while the lower limit 80W configuration will often fall behind the desktop RTX 3060 Ti. AMD’s RX 6800M likewise falls behind the desktop RX 6700 XT.
The benefit, naturally, is that you don’t fry your nether regions when gaming on the go, though battery life still tends to be far less than two hours for anything that really uses the GPU—no, a text-based Zork reimagining doesn’t count.