We resell a high-end CAD package that uses OpenGL. We have been using the ASUS V6600 & V6800 cards and have noticed that after opening a third window in this application, the system seems to switch to software based OpenGL. This initial sign of the problem is that the screen is repainted diagonally from the upper left to the lower right in several bands. I have seen other articles posted that suggest this is happening in other applications. This application does not have this problem using GLint based cards such as the GVX1 by 3D Labs. I too have sent e-mails to NVIDIA and ASUS tech support. I have not received any responses. It's too bad. We have found that the performance of the board is faster than cards twice its price! I did notice that dropping the # or colors to 65K will allow us to open more windows before we run into the problem. I tried the WIN.INI (VDA=0) but we are running NT. Is there a registry hack equivalent? Also does anyone know what the available registry entries are for these cards? Is anyone else using the GeForce with CAD apps?