The moment I discovered this issue, I went from WOW TBC Classic Gold having a 144hz main monitor with an additional 60hz monitor, to both my monitors operating at 144hz. I chose this as I did not want updating my system at this point as my old 60hz monitor was long overdue to be upgraded anyway.
However, I achieved this through upgrading to a larger main screen. This means that my GPU was now driving more pixels , at a greater frequency of. This meant that my GPU, which appeared to be fine for something as simple as Classic WoW had to be working. It was not up to the job.
With all addons off I observed that the game could flash even when VSync was turned off or switched on. It happened regardless of the fact that my GPU was over its limits. Zones like Nagrand with all its lush foliage would push and keep my GPU on the edge which eventually lead to it slowing down.
It seems that WoW does not like my GPU throttle. My CPU was barely moving at all, but with my GPU at its limit, I would see the flickering. The addition of addons exacerbated this flickering.
So I lowered my in game FPS limit to 60 , and cheap TBC Classic Gold the game became much better. It kinda sucks because after a few minutes of playing with a higher refresh rate it's obvious that you've getting back to 60 but it's a lot superior to the flickering I was experiencing.
