Tesla C2075 - Black screen


I have an i7 processor and a Gigabyte GA-Z68MA-D2H-B3 motherboard.

I installed Tesla C2075 on PCI express X16…

I installed a quadro FX 1800 on an other pci express slot.

When i tried to start the computer, noting, just a black screen .
(two green light on the tesla card)

I tried to change the quadro FX1800 with other graphic cards … nothing, just a black screen.

Any idea?

Thanks !