The DOOM 3 Hardware Guide
HardOCP has now posted "The Official DOOM 3 [H]ardware Guide" that will help you understand and maximize your DOOM 3 gaming experience. Here is an excerpt:
CPUs
AMD came out ahead in DOOM 3 performance with the strongest CPU in our tests, the Athlon 64 FX-53 processor. The Athlon 64 series of CPU is undoubtedly a powerhouse when it comes to overall gaming. Thankfully though, DOOM 3 is terribly forgiving to those of you that do not use the latest CPUs. DOOM 3 runs just fine on an Intel 1.5GHz Pentium 4 or an AMD Athlon XP 1800+. I came away from our testing at the id Software offices thinking that id has done a great job optimizing for both Intel and AMD platforms, and that DOOM 3 would run great on either platform readily and without issue. With that said, in our high end system testing, you can see where DOOM 3 and its image quality are allowed to scale upward with stronger CPUs from both Intel and AMD. Another standout was the ABIT IC7 system (i875) at 3GHz. The IC7 showed us that our previous thoughts about the aging i875 are indeed correct. The i875 may be a little long in the tooth as silicon goes, but when measured on performance there is little reason to replace the technology if you already own it. While the world of CPUs is changing a bit in terms of "better=faster," at this point in time when gaming is considered, more MHz are still welcomed. In the case of DOOM 3 though, the latest high-dollar CPUs are hardly a necessity as Athlon XPs and Northwood core Pentium 4s still bring more than enough of the needed power to the table.
Video Cards
While all aspects of a personal computer work together and rely on one another, with DOOM 3 performance the video card can easily be seen as the most important part of the equation. The BFGTech GeForce 6800 series of video cards stood out above all others in DOOM 3 video performance and image quality. NVIDIA's 6800 GPU is a monster on your side when it comes to chewing through DOOM 3's shadowy dark world. It would seem to us that the stencil shadow transistors that NVIDIA has included on their 6800 series GPUs are a defining factor in DOOM 3 video performance.
ATI's Radeon X800 series video cards also did very well in our tests, although performance-wise they did not come out on top. If you have an ATI Radeon of virtually any variety, it's likely quite capable of providing you with a great DOOM 3 experience. The VisionTek X800Pro is still easily one of the best all around video cards you can buy today. Thanks go out to VisionTek for their support of this guide, as they supplied most of our ATI-based video cards.