I have just purchased a second hand Viewsonic GA771 monitor for my old AMD DURON 750 system.
The system has an onboard graphics/video card which has been working fine.
No matter what resolution i set the display at 800x600, 1024x768 or more i can get the display pefectly square except for the top of the display which is warped in that it bends down slightly. There is not an option to adjust this in the menu and seems as i can get every other edge of the display square, i am wondering if there is a problem with the monitor.
It sounds like the monitor geometry settings require adjusting. These should be accessible in the form of buttons which should open up the menu for the various settings. Usually, there are settings for horizontal and vertical size and placement, degauss and moire adjustment, and geometry settings.
I am having the same problem with my brand spanking new CTX Pro 705F monitor,,,, only my screen is warped at the right hand side centre screen. It makes scroll bars look terrible!. I have tried all ways to straighten it out but i cant get it to look straight.
I have tried degaussing the monitor, and have played with the geometry settings etc. There is an adjustable pinch setting for the horizontal pinch but not for vertical pinch (unlike my 10/12 year old Samsung monitor)
All other edges are spot on including the bottom, which makes me think that it is not a pinch setting problem, but something which i may have no control over.
The monitors frame linearity requires adjustment, you will have to take it to a qualified technician to do this as you could destroy the monitor attempting to do it yourself. I would reccommend your local reputable PC repairers for something like this.