which os runs on it?
Mac OS X
Mac Pro
Mac OS X
what is the motherboard in a mac pro UNANSWERABLE is it a laptop or a desktop? It is a series of workstations and servers for professionals. It is one of four desktop computers in the current Macintosh lineup.
wiki:16108692
Mac Pro [SEP] Expansion cards
On the original Mac Pro introduced in August 2006, the PCIe slots can be configured individually to give more bandwidth to devices that require it, with a total of 40 "lanes", or 13 GB/s total throughput. When running Mac OS X, the Mac Pro did not support SLI or ATI CrossFire, limiting its ability to use the latest "high-end gaming" video card products; however, individuals have reported success with both CrossFire and SLI installations when running Windows XP, as SLI and CrossFire compatibility is largely a function of software. The bandwidth allocation of the PCIe slots can be configured via the Expansion Slot Utility included with Mac OS X only on the August 2006 Mac Pro.