To whomever it may concern, the Q70R now supports 4K 120hz on PC. I tested this a few minutes ago with an RTX 2080ti with the latest drivers, and I’m currently running at 4k/120 right now. It appears it was enabled through a fairly recent firmware update in conjunction with recent Nvidia drivers. You need to make sure the TV is running the latest firmware and you need to have newer Nvidia drivers as it doesn’t work with older ones. Just create a custom resolution for it in Nvidia control panel and voila, 4K 120. I was messing around with my 6900XT earlier as well, but didn’t think to try it on that card, so I am not sure if it works with AMD, but it definitely does with Nvidia cards.

Edit: When I let the TV go to sleep last night, it lost the custom res and reverted back to 1440p. To get it back, I re-added the custom resolution and set it to 4K in Windows display settings.