No video with 2 video cards

[Tripredacus]

I've just come back from trying all the BIOS settings, memory configurations and reading all the technical documentation on Intel's site relating to the motherboard and chipset and I am coming up with no definitive answer here.

Symptom: No video, PC posts but can't see anything. Initial POST beep sounds and Numlock key is workable.

Motherboard: Intel DG43NB

Video cards: PNY Quadro NVS440 PCIE x16, PNY Quadro NVS440 PCIE x1

Works when...: Take out the x1 card

RAM 2x DDR2 800MHz 2GB sticks

Alright so the computer will boot, but there is no video when both video cards are installed. If you take out the x1 card, you get the video. There are 3 x1 slots on the motherboard, and this happens no matter which one I try.

First thing I found out about was the memory. The Specification says that each slot only works with a maximum of 1GB, and supports up to 4GB maximum with 1GB in each slot. Yes the Spec says this board has 4 slots, but it actually only has two. So I went and got 2x 1GB sticks of the same RAM and put them in there instead. Here are the results of 2GB RAM (2x 1GB):

No POST/power cycling: with x1 card installed

Works fine: x1 card not installed

I tried to disable a bunch of things in the BIOS to see if it would work (went back to the 4GB config too). They were: USB, Onboard LAN, Serial Port, Audio and Firewire. This did not make a difference with or without the card.

The Spec also says that the memory address space for the PCI-E x16 with graphics is 256MB, and up to 512MB for the 1x slots. My ideas are that there is not enough memory address space with 2GB RAM for it to boot properly, and not sure about the 4GB issue. The integrated graphics also automatically determines whether to display video via VGA or DVI-D based upon the cards it detects, which is independent from specifying PEG as the primary display adapter. So the motherboard may change where the video is going to be output based on what is connected, so this could also be an issue.

Any clues about this problem?