NV3x/NV4X are designed for Doom 3
 

A similar thing happened with NV40 marchitecture where the NV40 has 16 pipes that can render one texture or 32 pipes that can render the same texture without color or Z values - something that Mr. Carmack requested from Nvidia. Nvidia knew at that time that not only Doom 3 would benefit from this kind of approach as ID software makes money by programming its engines and selling them to third party companies as well. Consequently we are talking about at least a dozen games that will use this engine.

http://www.theinquirer.net/?article=17497