Hi,

First of all, small circles and arcs (like vias), take alot of horsepower to draw especially for a PCB layout. Often, if vias or arcs are enabled and you are panning or zooming, they will bog a system down. Sometimes a video card will cache them and each time you move, it declares it dirty and flushes the cache. Try turing vias off (probably just disabling a display level) in P-CAD, Mentor, Allegro, Orcad, Zuken, or Express - I don't know what tool you are using. I know you can't run the tool that way, but eliminating arcs will tell you something about the problem. I assume you have checked the layout tool website for solutions to your video card if they have any.

Did the older ATI card that you had installed have the memory aperture configured? The Memory Aperture that ATI used in their designs uses a common address space in system memory to use as the system screen buffer (different than the on-card pixel buffer). In the older designs it used to speed things up alot - at one time it gave ATI an edge in the marketplace. You moved to a new card architecture and it may not have that capability. If it does, configure it and see if it helps.

One thing to consider is that the card is controlling multiple screen buffers. It probably has multiple processors, frame buffers, RAM, etc for that. Sooner or later, they all have to be prioritized and queued to talk to the host processor (your system CPU) and if that has not been managed efficiently, there may be a problem there too.

I assume that they are all set for high resolution and refresh rate. The more pixels to push around, the less time in between for processing changed screen buffer content. Some vendors X-OR the content with itself for faster execution time or just re-write over existing pixel buffer. If you are using DVI LED or LCD panels, sometimes the higher refresh times are wasted (unlike CRT displays). If you can't see a difference, reducing the refresh time from 75 Hz+ to 72 or 60Hz may make a difference. You have more processing time (up to 25% from 75Hz to 60Hz), during the Horizontal and Vertical Blanking interval (that's when you go to get changed video data from the host, process it, fill the input side of the video buffer, in preparation to clock it out to the output DACs), to process and push pixels around with the slower refresh rates. See if that helps.

I already assume you have shadowed the Video BIOS not that it makes much difference in high resolution graphics modes.

Ross