The controller is an HP Smart Array E500 Controller and the disk array is an HP Smart Array MSA50.
I have the bios boot order set to have the internal RAID 1 array as the first boot choice, then the CD drive as second, then 'Removable Devices' as third. During boot, the screen shows the E500 getting initialized. If I don't have the MSA50 connected, the boot screen then says '0 Logical Drives. 1785-Slot 4 Drive Array Not Configured. No Drives Detected.' but if I have the MSA50 connected, it allows me to press F8 and go into the array configuration utility.
However, in both cases it does not boot and just hangs there in limbo. When I remove the controller, the server boots up again fine.