Hi everyone, I'm interested in trading my MacBook Pro for a Mac Pro. I wanted to know what are the differences between the 4,1 and 5,1 Mac Pro in regards to the "motherboard". I've built my own desktops and servers so I wanted to buy an old 4,1 or 5,1 Mac and pretty much upgrade everything in it (CPU, GPU, RAM, DVD, SSD/HDD, etc.). I've heard that you can convert a 4,1 into a 5,1 through a firmware "update". My question is, is there any physical differences between the two Mac Pros (other than the upgradeable stuff including the CPU tray)? Are there any pictures of both motherboards? Thanks in advance!