I'm experiencing the same issues with the S1200BTS and HP P400 Raid Controller.
We utilise the HP P400 extensively for it's excellent Linux Support and we are now left looking for alternative Server Hardware
I have firmware v5.12 and the intel S1200BTL board.
I aslo cannot get this raid card to work.
It will not detect in any slot except the one the fartherest away from the CPU.
But if in that slot, it does its first line about detecting the array, and then the system hard reboots.
When will there be a fix for this?