We do not have motherboards that support 8 disks. The following link will provide you the products that have 9 SATA ports; however there are 6 Intel SATA ports, 2 Marvell SATA ports and 1 eSATA.
Something very important for you to know is that you cannot combine Intel SATA ports and Marvel SATA ports to create a Raid Array.
So that means, you can use 6 hard drives maximum to create RAID.
Are there any plans to release chipsets with native support for 8-disk arras?
What is your best PCI solution for an 8-disk RAID 10?