DL120G6 won't boot with PCIe->SATA card & connected drive

Hi,

I've got an DL120 G6 machine with 4xHDD connected to the mobo controller in a RAID10.

I am trying to add an SSD to be used as a cache space for an app server.

The mobo does not support more than 4x HDD connected to it, so I bought a PCIe to SATA3 expansion card. (Its chip is Asmedia 1061), and an Intel 535 SSD.


However, when everything is connected, the machine fails to boot into Windows. (If I disconnect the drive's either power, or data cable, the boot process completes even with the PCIe board in place.; I also tried with another HDD just to be sure the problem is not in the SSD).


When I power the machine, everything seems fine. Mobo's boot screen comes up. Then the HP NIC boot agent, HP b110i RAID controller and the PCIe card screen is last (showing the connected SSD/HDD).
On neither of the screens there is an error of any sort whatsoever, nevertheless the boot process stops just before starting Windows (Server 2012). The screen is blank with just an underscore blinking on the top left  end of the screen. I tried disabling the SSD in the BIOS boot order with no result.

Any suggestions?