Apple explains that these "Space Gray" cylinder Mac Pro models are "designed around an innovative unified thermal core" and have not only faster processors than earlier models but also dual workstation class graphics processors, faster memory, and faster PCIe 2.0 x4 flash storage. Instead of internal expansion, the system provides extensive high speed ports for external connectivity options.
Connectivity includes six Thunderbolt 2 ports, one HDMI 1.4 UltraHD port, 4 USB 3.0 ports, and Dual Gigabit Ethernet ports in addition to 802.11ac and Bluetooth 4.0.