Hi there, I have an old mac 1,1 2.66 dual-core intel xeon and im stuck on Lion. I would like to increase the speed and also upgrade to El Capitan. I see than you can upgrade the intel processors. Would you happen to know what processors are the top speed that are compatible with my macpro? If I upgrade the processors will it run El Capitan without having to tweak the boot software? I also hear that Mac Pro 1,1 and 2,1 as well as the 3,1 and 4,1 are now "dead ended at El Capitan. Would it be better to just buy a 5,1 off of Ebay? My budget is less than $400 so I don't know if its worth it to upgrade. Thanks for your help.