Hello I have a 8400GS 512MB graphics card, model #ZT-48MEH4M-HSL, that fails the Power On Self Test (POST) of my Dell 4700 system. The card worked previously however the POST would always present the message "PCI - Express Switching to X1 mode press F1 to continue" each time the system booted. However, I unistalled the card to review it's SPDIF connection and now it fails the POST and my system will not boot with the card in the PCI-express x16 slot. Is the card just incompatible with my system or could it be defective? Thanks!!