One other thing. I suggested those that have the problem try altering the clocks on the video card to see if it made a difference.
However, if the problem is located after the RAMDACS and before the video connector, altering the internal clocks of the video car may not have any effect.
For this, you would have to alter the monitor's refresh rate and the horizontal clock as well. This can cause a squashed video, which might make it more difficult to see the problem, but it is something to try. It should not have to be changed much.