While many initially worried how upgradable Apple’s new 2013 Mac Pro would be when they first announced it on stage back in June, it turns out that both the RAM and the built-in SSD are actually fully user upgradeable and replaceable. This is essential for many professionals who keep their machine for years and enjoy customizing it.
Even better, replacing either the RAM or SSD is extremely simple – and Apple provides instructions with a pair of helpful support articles!
Replacing the RAM (direct link to support page)
According to Apple’s official support guide, replacing the RAM in your new Mac Pro is a matter of simply removing the enclosure, removing the old RAM, and snapping the new RAM back into place – as illustrated in the above diagram. Make sure to check out Apple’s Mac Pro RAM spec page to ensure you buy the right type.
Replacing the SSD (direct link to support page)
Replacing your Mac Pro’s built-in flash storage is almost just as simple – although we’d caution that your options are likely to be very limited, depending on which manufacturers actually make replacement SSDs for the new Mac Pro’s specific form factor. All it takes is removing the enclosure, popping out a screw, removing the old SSD, and adding a new one of your own. Very simple, accessible design.
(Ref. http://www.mactrast.com/2013/12/replace-upgrade-ram-ssds-new-mac-pro/)