I have been having confusing results with the Solo x2 cards and the CalData FASTA-6GU3 cards, but
am able to boot OS X or Windows 8 installed on the x2 card
with the CalData installed as well.
My problem is that I can't have 2 ea. Solo x2 cards installed, one with OS X, and one with Windows, and
get Windows to boot ("Boot Disk Not Found") with or without the Caldata card. Using either x2 card alone boots the attached OS just fine, again with or without the CalData card.
So I don't think my issue is with the interaction of the CalData and Solo x2 cards. I have my CalData in the top slot (4) nearest the disk drives, and the Solo x2 cards in the middle slots, with the graphics card on the bottom slot (1).
Currently my 5,1 Mac Pro is running great with the following layout:
PCIe Slot-4: CalData FASTA-6GU3
PCIe Slot-3: Sonnet Tempo Pro dual SSD with OS X RAID-0 (pair of Crucial M4 512GB)
PCIe Slot-2: Solo x2 SSD with Windows 8 (Crucial M4 256GB)
----
PCIe Slot-1: Sapphire HD 7950 graphics
I have seen several threads here claiming that the CalData and Solo x2 cards are incompatible ... but they are working together for me (at least for now)!
-howard