Bios Mods -The Best BIOS Update and Modification Source

Hi, 

I have ASUS P8P67 and i5 2400 (turbo overclocked + 400MHz) and I'm thinking about buying xeon E3 1280 (3.5 / 3.9 stock) or i7 2600 (3.4 / 3.8 stock). Xeon has higher clock speed and the same price, the question is will it work without BIOS modification and will turbo overclocking be possible?

Try to install new CPU and tell about results.