For the money the architecture is almost identical to a Mac Pro 4-5,1 but I think it can only support max the X5680 or W3680 hex core CPU running 3.33Ghz. The CPU heat-sinks aren't good enough for the high clock hex cores unless you polish the contact plate of the heat-sink and the CPU die also and use really decent thermal paste. Chipset is limited to SATA2 but I'm pretty sure they will support Samsung SM9XXX PCIe blades with an add on PCIe card or a PCIe SATA3 card.. 16000 geekbench multicore for a single hex core Xeon bought off ebay and dual socket nearly double that for the money is a great system. Like my dual socket 3.46 x5690 Mac Pro 5,1 with a PCIe blade, OS X and Windows ;-)