Hi, The no boot might be caused by voltage differences. According to the Xeon Wikipedia article: The voltage range for the "Paxville MP" is 1.2625-1.4125 V. The voltage range for the "Tulsa" is 1.1-1.35 V. I'm having similar issues, but much smaller goals for now. Getting the Tulsa to run would be fantastic. Have a look at a thread called Dual-Core-Xeon-support-for-HP-XW6200 on bios-mods.com (sorry, I can't post links)