A lot of server boards are limited to the 95w lga 1366 cpu's. Usually down to availability of power on the boards. Asus' Z8NA-D8 will only take 95w cpu's and has one eps plug, its bigger brother has 2 eps plugs and can take 130w cpu's
I have two BNIB X5650, but I am not gonna be using your X5680 for folding.. they'll go in my ESXi server.
If you are still willing to trade, please shoot me a PM.
thanks,