Try the legacy kexts posted in this thread at insanelymac, it may work with the ICH9 in RAID mode, of course you wont be able to access any arrays...
I never have similar problems with AHCI, it works with Apple drivers and unless something is wrong with your motherboard it should not have DMA problems specially on Intel chipsets.
I would check the motherboard settings and make sure you are using plain Apple AHCI drivers.