Having video issue, not sure how to describe it I have a mid-2009 Mac Pro with dual video cards.  About a year ago I started noticing an odd video artifact on one of my monitors.  I'd be scrolling something vertically and part of it would freeze, then catch up with the rest.  I'm now seeing it happen horizontally as well, while watching a video.  In each case it seems to be isolated to one area of the screen, though I'm not sure of that.

What could be causing this, and/or what are the right keywords to research it online?  Searching for video and split was not helpful at all. :)
You already installed the official drivers
nVidia to see if this problem is solved?
is a two graphical cards Nvidia GT120?
look here: http://www.geforce.com/drivers