The Basis - Mac Pro (Early 2008)

Here is the Mac Pro which I started modding back in 2009 until 2014:

  Model Name:    Mac Pro
  Model Identifier:    MacPro3,1
  Processor Name:    Quad-Core Intel Xeon
  Processor Speed:    2,8 GHz
  Number of Processors:    2
  Total Number of Cores:    8
  L2 Cache (per Processor):    12 MB
  Memory:    14 GB
  Bus Speed:    1,6 GHz
  Boot ROM Version:    MP31.006C.B05
  SMC Version (system):    1.25f4

So it is an Early 2008 Mac Pro with 8 cores in 2 Xeon 2.8 processors.
 http://lowendmac.com/2008/mac-pro-early-2008/ provides further useful information.

The system now runs OSX Mavericks 10.9.4 and will qualify for Yosemite.