well I bought a 2012 Mac Pro 5,1 that had four 2tb wd red drive , 64 gb ram, it's a 3.33 12 core machine when it arrive it had a standard nvidia gpu pci card, a USB 3 pci card and the by was disabled and a USB but device installed. I added a Sata dual drive pci card and two 1tb wd ssd drive in striped raid, a wifi/bt4 pci card abd replace the standard nvidia gpu with a pc nvidia GeForce 680gtx gpu connected to three acer 24" flat screens circa late 2012 plus hooked up my Wacom cintiq, added a webcam and mic and speakers. That the race horse I have now. Oh one more thing was added a esata raid enclosure with four wd red 4tb drives in raid 5 iirc. I'm wanting to add some more pci cards but the machine is out of slots I looked on the net and found that you can go pci out to a pci enclosure but he'll they wanted 3 grand for the one I saw. Looked on eBay same thing no used ones out there where do you find a used pci enclosure they got be around as it appeared to be the thing before the Mac Pro cylinder was released to add more to your Pro. I'm sure those that jumped on the poorly designed new Mac Pro sold theirs and regrets it now. So where are they now used?