I did some more testing and it's definitely the board limiting fsb, tried numerous cpu's I had around but none got any further. NB volts & VTT do nothing to help, played with the GTL's and PCIE freq also. Seems like something behind the scenes is stopping it, hangs on post code 1P (which is nothing) which is just prior to 51 (Allocating resources to the PCI bus). Sometimes gives a memory error so maybe the 5:4 mem strap is doing it, maybe I need FB-DIMM's that can do 450MHz+ @ 1:1.