I have an Intel L440GX+ motherboard which has a builtin Cirrus Logic GD
5480 graphic chipset, and a Diamond Viper 550 PCI card. By using the
Diamond, the Cirrus is disabled. The Redhat installer just picks the first
card that it finds. It should either figure out which is the active card,
or if it can't, it should query the user which card to use.
Did you disable the Cirrus in BIOS? This is required in order for the installer
to recognize the "correct" card.