My instructions are based on this article for getting Arch to support the 88SE6145 SATA II PCI-E Marvell controller. That is one of two SATA controllers used by the Intel BOXD975XBX2KR LGA 775 Intel 975X ATX Intel Motherboard.

Here is what we must do.

Blacklist the Marvell PATA kernel module.

# /etc/rc.conf
MODULES=(... !pata_marvell)

Enable Marvell AHCI module.

# /etc/modprobe.d/modprobe.conf
options ahci marvell_enable=1

Update ramdisk config.

# /etc/mkinitcpio.conf

Recreate ramdisk.

mkinitcpio -p linux