Ok, so I have an odd problem. I've had my system for about two years now with an Asus M3N72-D motherboard with built in video and two Geforce 9800 GT's in SLI. Everything has worked great until this weekend.
This weekend I was troubleshooting some hard drive issues and, to make working in the case easier, I took out the two 9800 GT's and used the on board video. Now I can't get the PCI-E video cards to work. I've reset the BIOS, confirmed that the video cards have power, but they don't work. I only get a signal from the onboard video and when I open Device Manager, the PCI-E video cards aren't detected.
Does anyone have any ideas? I've never seen this happen before.
Are you plugging your vga/dvi cord into your 9800's and not your onboard one? I know it sounds stupid but it happens. If that's not it try messing around with the bios or updating the drivers might help.