Was going to suggest exactly the same.
I presume you have nothing attached to the Promise SATA's or IDE sockets, and are using the ICHR5 jobbie for your RAID0.
Whip into the BIOS and disable the Promise controller, and see how that improves things.
There could also be other things within BIOS that you may have enabled which you do not need (other drives set to auto, serial/com ports, etc)
Waiting to hear back.