I think it was hexen that implored you to buy a 486 if the viewport window was set to the smallest size. That's all I could think about when I saw potato mode!
Originally I thought it was a text printed on the screen, but looking at the art assets in Rise of the Triad, the "buy a 486! :)" actually part of the background graphic. It's just normally hidden by the play area unless you use the smallest size.
no, it was raise of traid (or whatever the correct name was)