Omg....your comment is wrong on so many level I'm not even sure if it's Troll or not
There's absolutely nothing special about internal hard drives. Mac Pro doesn't have them, it has an embedded SSD module. Hard drives are external on Mac Pro.
We're in 2015 right? So SSD didn't conquer the world...right?
Do you know how incredibility frail hard drive are? My mother lost 10 years of picture because they accidentally bumped their external hard drive while it was writing something. Sure you can but it on the personal network far from any harm, but it's not something "parents" do by themselves.
You can attach any graphics card, or really any PCI or PCIe card supported by OS X via thunderbolt. Get an external card cage and enjoy.
Yeah.....what a great option.....upgrading my graphic card in 2 years with an external card cage...why are we even still buying desktop nowadays?
If the PSU fails, you have Apple replace it. If the logic board fails, you have Apple replace it.
......really? Do you honestly believe that Apple will replace my PSU or motherboard free of charge in 5-10 years if it ever fail? You know that with desktop, I can diagnosis the problem and replace the broken part in less than a day right?