This is on an HP Z600 Workstation. Plugged in both WD5000HHTZ 's and they run fine as secondaries, did disk checks, tried to install in Raid 1, Raid 0, and individually with no luck. Goes through install, but when completing installation after reboot , system says that it is unable to install on hardware.
I found the drives are able to be installed on separately. I think it is a conflict with the Intel 5520 chipset when running in a Raid format. Unsure if it might be due to the advance formatting or the drives not downgrading to SATA II automatically when in Raid.