4k@144hz

Hi, I want to ask for your advice. I bought a new monitor (Asus Rog PG27UQ, 4k 144hz) and I wanna play 4k @144hz (or at least @120hz). Currently I have 1 GPU Gigabyte AORUS GeForce GTX 1080 Ti Xtreme Edition 11GB, my question is, what do I need to do? Do I buy another 1080Ti for SLI...