I don't mean to disparage OWC in any way. But in looking around for used mac pro's I found their ads to be confusing. I called them but did not get much reassurance for this particular "2010 2.66ghz 12 core model" I was told that it was upgraded from a 4 core. I can't find anywhere where this type of processor exists? Also, anything to be wary of? I would prefer 2 cpus at 6 cores. Why I don't know. Just seems better weight distribution. OWC ad, under specs: Machine Specifications Apple Mac Pro - Mid 2010* 2.66GHz 12-core Model ID: MacPro5,1 View how to find model ID Processor / Memory One 2.66GHz 12-Core Intel Xeon X5650 processor 32GB (4x8GB) 1066MHz DDR3 ECC SDRAM memory Four Memory Slots OWC Memory Upgrades: Add up to 96GB of memory. OWC certified for up to 96GB of memory.