Windows 7 Not Detecting PCI Slots After Format?

I'm having major problems with my PC at the moment. It was all working well but it was due for a clean and I had all the files I wanted off the Harddrive so I put in the Windows 7 CD and rebooted the PC.I changed the BIOS so the CD/DVD drive was 1st priority and let it reboot itself. The installation went smooth. I initially had 2 partitions on the Harddrive, I deleted them both and created 2 new partitions and installed Windows onto the smaller one. Everything seemed fine but when I got into Windows I noticed I couldn't set my resolution to the normal dimensions like I always could after a format. I checked Device Manager and under the Display Adapters and Sound Controllers menus there is no sign of my HD4890 and Xtreme Music. I know the HD4890 is working at least because I have the monitor plugged into it and it works but Windows doesn't detect the card at all and is running off the onboard because it's the only choice it has.I tried installing drivers for the motherboard, graphics card and sound card but it didn't fix the problem. I also flashed my BIOS with the latest BIOS update from the Gigabyte website. I've tried formatting again 3 times which made no difference. I've tried removing both cards from the PC and booting it up, turning it off, replacing the cards and booting it up, but Windows still didn't detect either of them.