Hello, I am using a mac pro 2008 with a Mercury Accelsior E2 PCI express with an internal Solid State Drive on the card and 2 external SSD drives. I am using Mac Os X El Capitan and it's installed on the SSD that is physically on the card. and this is the startup disk. When the external drives are "OFF" the computer starts up just fun. But, When the 2 external drives are "on" the computer won't startup, as if it can't find the startup disk. So I can't leave them on. Any ideas?