5400x1920 @ 120 Hz, that's 10.4 megapixels.
I was able to drive my puny 2560x1600 (4.1 megapixel) display with decent GW2 performance at maximum settings with a single Radeon HD6970. My PC was pulling over 400 watts from the UPS and there was a lot of heat being discharged from the case while I was playing, but it played pretty decently. I didn't check the frame rate, but I'm certain that it was less than 60 fps.
i7-4770K, H70, Gryphon Z87, 16 GiB, R9-290, SSD, 2 HD, Blu-ray, SB ZX, TJ08-E, SS-660XP², 3007WFP+2001FP, RK-9000BR, MX518