Okay, so, I've been going through a series of upgrades, probably in the wrong order, on my MacPro 1,1. I updated to El Capitan using the Piker method. Now, I want to add a pair of Xeon X5365 3.0GHz CPUs, which requires me to upgrade the firmware to 2,1. Unfortunately, I can't get the "Mac Pro 2006-2007 Firmware Tool" to work. Do I need to be in a Snow Leopard or Lion environment for it to work? If so, I am stuck with trying to get anything other than El Capitan to boot up. Any advice, please?