1440x900 either at 75hz, 72hz or 60hz. I'm running a 7900GT and each time I try to change the resolution my screen gets all garbled like the monitor can't run at that resolution or refresh rate. Its running at 1280 x 1024.
I just looked ont he BenQ website and that is the correct resolution, its a little bizarre, because most nvidia cards should at least be able to create custom resolutions. To be honest it sounds more like a monitor issue, not a card issue to me.