If you still have the old motherboard you can buy an old Xeon X56xx and use it as a drop in replacement in the LGA1366 socket. An X5650 for instance cost about

If you still have the old motherboard you can buy an old Xeon X56xx and use it as a drop in replacement in the LGA1366 socket. An X5650 for instance cost about $25 on ebay, is clocked at 2.66 GHz like the i7 920, has six cores, a TDP of 95W, and overclocks really well. I don't know if most i7 motherboards support ECC, but the CPU supports it. The LGA1366 motherboards still fetch some money too, if you'd rather sell it.