My Dell LCD e197fpf 19" 75Hz monitor is not outputting the full framerate it is capable of when put at resolutions above 1024x768.
I expect my monitor to output the framerate given by the GPU up to the maximum that the monitor can display. However, if I take a computer game which I know doesn't tax my GPU or CPU, eg. Counter Strike: Global Offensive, especially on low settings, and I set my resolution to 1280x1024 or higher then it caps my framerate at about 40fps. I deduce this lower framerate by eye from decades of gaming experience but I cannot quantify the lower rate exactly.
The moment I set the game to 1024x768 or lower it suddenly seems to unlock to 60fps. Indeed when I get the game to show me the framerate the GPU is outputting at 1280x1024 or higher res then it's over 100 (both with and without vsync), but the monitor only renders 60fps when I have a resolution of 1024x768 or lower. I have tested with horizontally wider and vertically narrower resolutions such as 1280x720 and they give the same frame rate locking problem.
Because I know the monitor can do 60fps since I get it at lower resolutions. I thought it was the GPU's job to just output pixels to the monitor, and there's no computation done between the GPU and the screen, so why is the res capping the framerate?