FSB??? Front Side Bus

I am interested in purchasing a mac pro but I would like to know what the FSB is on the computer because it is the true limiting factor to your speed (sorry to burst you bubble but you crappy ram may be holding the mighty processin the CPU back). I can build a computer that has a FSB of 3000MHz Faster than any computer on the market... except possibly this one. As i can not find this statistic in any of the mac pro web pages I thought that somone out there had to know it. Thanks for any help.