My Mac Pro with 1900XT and two 30" ACDs worked flawlessly. Never a dancing pixel. After I upgraded to the 8800XT, I started getting the green pixels on one of the monitors. When I switched their video plugs on the card, the pixels showed up only on the other monitor. With 10.5.2, I only got the pixels very occasionally on start up. When I upgraded to 10.5.3, I now only get them very occasionally when the machine wakes from sleep, never on startup.