MrM3kon,
The problem may be quite straightforward, which is that the connectors from the drive bays using an SAS drive to the motherboard have to be moved from the SATA ports to SAS ports on the motherboard.
See the motherboard diagram on page 82 of the z800 service /maintenance manual.
There are 7X SAS connectors on the bottom right of the motherboard:
7 6 5 4 3 2 1 0
And the 5X SATA connectors are the row above:
5 4 3 2 1 0
So, the idea would be to move the cable connecting the lowest drive bay to the 0 - far right- connector on the motherboard, the second drive bay cable to the "1", and so on.
Cheers,
BambiBoomZ