I have an ATI Radeon HD 2400XT Video Card 256MB DVI PCI Expres, I installed the card but my computer is not recognizing it, I've disabled the onboard graphics (but have not uninstalled the drivers yet..) and choose PCIe in BIOS after that the fan goes from full blast to regular speed about 7 times then my computer boots up and the video comes through the onboard graphics even though its been disabled and moved from primary video.
I have also removed the CMOS battery with still no success.
No video is broadcasted from the card.
And it also does not show in the device manager.
I've reset the CMOS
Upgraded the BIOS with my manufacturers latest update
Running latest version of windows Vista Ultimate SP2 32bit
Motherboard is an Asus A8N-LA
BIOS type Phoenix Award
The computer was a Compaq but i swapped the motherboard from a pavilion desktop, upgraded the Ram, added a 1 trerrabyte HDD
I have a gateway with the same processor and pheonix award BIOS and I am also having the same problems as you, I have tried just about every solution and nothing has worked, maybe we just have the crappiest BIOS around.