You guys better read up before doing rash things like buying an extra gig of ram...
http://www2.hardocp.com/article.html?art=NjQ0
From the article:
"Ultra Quality is the cream of the crop for DOOM 3. In Ultra Quality nothing is compressed. Normal maps, and specular and diffuse lighting are all displayed at full resolution with no compression. Because of this, there is a tremendous amount of texture data needed on the video card, upwards of 500MB. While it will run on lesser cards, you may experience hitching or pausing due to the graphics card having to swap textures in and out of its memory buffer. That is why this setting is recommended for 512MB video cards. There is nothing stopping you from trying this quality setting if you want to, just keep in mind that the memory load is huge."
From Robert Duffy's .plan (
http://www.bluesnews.com/plans/313/ ):
"In Ultra quality, we load each texture; diffuse, specular, normal map at full resolution with no compression. In a typical DOOM 3 level, this can hover around a whopping 500MB of texture data. This will run on current hardware but obviously we cannot fit 500MB of texture data onto a 256MB card and the amount of texture data referenced in a give scene per frame ( 60 times a second ) can easily be 50MB+. This can cause some choppiness as a lot of memory bandwidth is being consumed. It does however look fantastic and it is certainly playable on high end systems but due to the hitching that can occur we chose to require a 512MB Video card before setting this automatically."