PCIe SSD not recognized

[Itooth]

My Set up

1. ASUS Rampage IV Extreme

2. Cpu Intel i7 3970 x

3. Cosair Dominator 64 MB 1333Hz

4. Cosair Ax 1200i PSU

5. Three Nivida GeForce gtx Titan 2795 HydroCopper water cooled GPUs in 3way SLI (slots 1,2 4)

6. Mushkin PCIe 1920 GB SSD in slot 6

7. Two Western Digital HHDs in RAID 1

8. WinOS 8.1

Trying to use SSD for OS and HHDs for data storage

BIOS recognizes SSD and HHDs, but can't boot up from SSD (able to load winOS 8.1 to HDs and boot from them) when in WinOS 8.1 disk manager does not show SSD at all.

CPU supports 40 lines of PCIe. The SSD requires x8 lines. Is the problem the limitation of CPU or something else? Any thoughts/ suggestions would be helpful!

Thanks in advance!

Itooth