HP Z820 + Dual GPU detection issue / Quadro 6000

[Bart10152]

I have recently been unable to detect a second gpu on one of my workstations. Up untill recently, the workstation has been running perfectly with one Quadro 6000, on a single cpu.

A few days ago i plugged in a second identical graphics card, hooked up all the necessary wiring, and did not bridge the pair into a SLI configuration.

Upon launch, I get a message stating "941-PCIe Devices Installed in slots 3 or 4 with a single CPU." I am also asked to press F1 for Boot at this time.

I have reinstalled the GPU drivers while the second GPU was plugged in but for some reason, CPU-Z and my current software for 3D development Blender, are not seeing the second card.

I have also seen some technical readouts from CPUID that the maximum ammount of PCIe link width is x16. Does that mean that I can only use one GPU?

Thank you in advance!

Technical data:
 Intel Xeon E5 2640

Mainboard HP 159B

BIOS 06/27/2012

RAM 32 Gb

[DGroves · Accepted solution]

3rdSlot available ONLY when 2nd. CPU is installed, this is documented in the user and service manual for the z820

either install a second cpu the same as the existing one or use another pci-e slot

i also recall that this applies to the4th pci-e slot as well, which is why those 2 slots are a diffrent color (white)

instead of black on my z820 (which does have dual cpu's for just this reasion!)

you should have a 16x slot (which runs at 8x) free down towards the edge/bottom of the case

this will work fine for SLI 

[Bart10152]

Thank you. I did not know this.

The only problem with this is that the GPU is squeezing down on the wiring located at the base of the case.

I wanted to hook up a third GPU but as it seems, I need a second CPU aswell.... Kind of pointless if you ask me.

Is there a way to allow the two PCIes to run through to the existing CPU?