very wierd monitor problem

well this makes no sense to me so hopefully it has happen to someone here and they know what to do. i started by installing a defective raptor hard drive, once i figured out it was not working, i put my old 7200 rpm back in, formatted and cleared cmos, well when it restarted, bios/post lettering colors were dark red/purple so i figured my new monitor is shot, so i hooked another monitor to it, and it displayed fine, heres the catch i hooked the original one into another pc and it displays fine, im completely lost now, ive tried everything, colors that should be white are red/purple depending on shade of white anyone have any ideas