Display Settings

I need to know how to get into a graphics option mode upon startup of RedHat

8.0.    I have a Dell 1503 flat panel and whenever I try to boot up RedHat,
I get a message that it will not recognize the display size.  I'm using a
Dell Optiplex GX110 and cannot find anywhere to adjust the setting in the
BIOS.

Thanks,

Jeff James
Systems Administrator
US Foodservice / PHX
(602) 352-2240