Ask Max: Getting rid of vertical stripes on my display
Upon installing an OWC G4 500 MHz. processor in my original B&W G3 350, my display shows vertical green stripes. I am currently running OS X 10.3.9. However, the vertical stripes do not show up if I boot directly into OS 9. I contacted the vendor of the G4 (OWC) and they couldn't figure out what the problem was. Although I can live with the vertical stripes, it would be nice if I could get rid of them. Have you seen anything like this before? The green stripes only show up when a Finder window or the Dock is displayed.
Video artifacts can be the result of several causes. Drivers would be the first thing to check and the simplest fix. During your upgrades to this B&W PowerMac did you install a new video card? If you did, look for an updated video driver for OS X. Also look to see if the processor upgrade card you are using has two drivers. Perhaps one is for OS 9 and the other is for OS X, and only one was installed. Because the green lines are only displayed in OS X and not 9, it suggests a problem with just the OS X operating system. However a hardware problem can cause this as well. Bad video memory on your video card can result in symptoms like this. I have seen video RAM issues that only appear in OS X and not OS 9, so it would fit your experience. The only way to fix bad video RAM is to replace the card. However, before you go and buy a new video card, I would first check the next reasonable suspect. That last suspect is your firmware on the logic board. Follow this link to a list of firmware upgrades and check to make sure that you are up to date. If all else fails, replace your video card. The ATI 9200 is a good choice.