The EVGA FAQ for this board shows these for CPU support:

Due to the chipset, ONLY Dual Xeon QPI processors will work.

Intel Xeon E5620
Intel Xeon E5540
Intel Xeon X5650
Intel Xeon X5680
Intel Xeon X5667
Intel Xeon X5677
Intel Xeon X5550
Can anyone confirm any other (cheaper) CPU's? I want to get an SR-2, but need to ease into it for cash-flow reasons