Fidgetmaster :
I'm not sure man, someone might have modded the BIOS to get it to work. I think that's mainly what it is the bios just doesn't recognize it right?
Yep, that should be the main issue since the board supports CPUs like the i7 990X too, so running the Xeon X5650 should be easy.
I couldn't find anything with Google, so if you can find somebody who was able to do this, you should try to contact them directly.