Can the fastest consumer desktop GPU available beat the fastest laptop with SLI graphics? Not quite, but it's at least 50 percent faster than any gaming laptop out there equipped with a single GeForce GTX 1080 GPU.
https://www.notebookcheck.net/Nvidia-Titan-RTX-is-just-15-percent-slower-than-a-laptop-with-GeForce-GTX-1080-SLI-graphics.400556.0.html