I'm in the exact same boat. I've tried every single suggested fix from these forums and the Reddit compiled list. Nothing has worked. Aside from restarting the game, the only other method I found was to hook my PC up to my 60hz TV and play that way. Not what I had in mind for playing Destiny 2 on PC. My PC specs are the same as yours. Very, very frustrating, especially when we just want to enjoy Forsaken content.