why the frak does steam do this

[gearsman]

ok why can't doom 3 be played on ultra on steam, on my cd version it runs on ultra perfectly fine. Everytime I apply ultra to the steam version it stays on low and just syas it on ultra no change in graphics at all. I'm not gonna buyt the bfg edition so you gusy better fix it. I've tried it all, reinstalled it, compatibility mode, mods, everything I could think of why isn't it working.