And Suddenly . . . . Silence

[Dirk Broer]

CPU: if 6380 series, a 6380 (115Watt tdp) and not a 6386SE (140Watt tdp). You might also want to consider the 6370 series, also 16-core and also 115Watt tdp and less expensive.

Motherboard: If in future you want more upgrades buy a quad mobo, like the SWTX format SuperMicro H8QGi-LN4F. The mobo is also able to support two PCIe 2.0 x16 cards.
It will go to 1TB of RAM to support 64 cores with 16 GB of RAM each. It is HUGE though. They also have dual Opteron mobo's that will support 512GB of RAM and that are of EATX format.

OS: You can use Windows if you are more familiar with it, but Linux would probably give better performance.

PSU: A 80 Plus Gold, Platinum or Titanium certified PSU, e.g. The Corsair AX1200i, but you might want to check with the mobo retailer whether that PSU will have all needed connector plugs for a SWTX board. EATX won't be a problem.