as far as i know it depends on the card, with my old ti4200 if i hit f8?-f10? not sure which one it's been awhile, it would give me the option to enter the vga bios, where i could change anything. but that don,t work on my 5900.
so i guess if you got an older card you got a chance, but i doubt it will work on a newer card. anyone feel free to correct me if i'm wrong