If you have a Power Macintosh 9500 series computer you may notice that the screen blinks off and on for a second during the startup process.

The video 'blinking' or 'blanking' is normal behavior for the Power Macintosh 9500 series computer's video card and does not signify a hardware problem.

The reason that the video goes black for a short time at startup is that the video card initially uses the driver contained on the ROM of the video card. Early in the startup process, a newer video driver contained in the Graphic Accelerator extension is swapped in. It is during the swapping of the video driver that the blanking occurs. This is considered normal.

As a method for troubleshooting you can prevent the 'software' video driver from being swapped in and force the Power Macintosh 9500 to use the video driver contained on the ROM by holding down the Command-Shift-N-D keys at startup. You will notice that the video 'blanking' does not occur because the video driver is not being swapped. You can also remove the Graphic Accelerator extension to prevent the video driver from being swapped as well.

This troubleshooting tip can be helpful for a couple of reasons:

• It can be used to demonstrate that the video driver is actually being swapped because it does not 'blink' when the video driver on ROM is used.

• If the 'software' video driver is corrupt for some reason you can revert back to the video driver in ROM to determine where the problem might be (that is, it can be corrupt software or a bad card).

IMPORTANT: Since the video driver in the "Graphic Accelerator" extension contains a newer video driver, you should bypass this video driver for troubleshooting purposes only. Running the system off of the ROM based video driver continually may produce unpredictable results.

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