I've been running my P4 1.6A @ 163 FSB for about a week now, and ran Prime95 in WinXP Pro for 24hrs straight to check the stability. I also tried 166 FSB, and ran Prime95 for 12 hours without any problems, but 3DMark2001SE shows a few visual anomalies when I loop it, so I went back to 163 FSB...