I figured it out, its part of the NVIDIA upscale algorithm thats in Cataclysm. It disables AA. Open up the ConsoleVariables.ini and remove the below entries. If you want to use the upscale algorithm in the future. you need to set those params again.
; NVCHANGE_BEGIN: Improve super-sampling
r.Upscale.Quality=4
r.ScreenPercentage.Editor=1
r.ScreenPercentage=100
r.PostProcessAAQuality=0
; NVCHANGE_END: Improve super-sampling