I have an ASUS A7N8X Deluxe MB. 1 PC2700 DDR333 RAM module and I just went from an Athlon Thunderbird 1.4Mhz to an Athlon XP 2500+ Barton core (socket A). My mainboard supports up to 400Mhz FSB and I originally had it set to 200Mhz with the 1.4Mhz Athlon. After updating my BIOS to the most recent version, I can run the system and have it stable at 200Mhz FSB and 266Mhz FSB but when I push it up to 333Mhz FSB, it randomly reboots when in Windows XP. I am running at Optimized settings for my memory (7,3,3,2.5T). I also tried changing the settings to 9,3,3,3T but it still reboots. The temperature for both the MB and CPU are about 100 degrees F and well below the limits. I wasn't sure how to debug this and was looking for some help.