2002

Obviously with a Voodoo2/3 you can't run on the highest for anything after 1999+ due to the sudden rise of 512x512's, 32-bit textures and DXT1

You wouldn't use a V2/V3 with that system. the Voodoo 4/5 and Pentium III came out at close to the same time, so you would want to use one of those because they support the features that LeiLei mentioned above. Voodoo 2 would be especially bad because when you pair those with a really fast CPU, they heat up and a V4/5 runs circles around V2 SLi anyway.

And 30fps really isn't playable because as soon as the CPU or video card get busy, your frame rate will dip into slideshow territory. I would consider 30fps to be the minimum with 50+ being playable.

30fps is nice, as long as it is constant and doesn't dip lower than 20 fps at any given moment. Voodoo 2 and 3 were great all the way to early 2000. Around that time came the sudden rise as leileilol noted of a lot demanding features.
The Pentium 3 Tualatin 1.4Ghz should have been fine all the way to 2003 perhaps even early 2004.

I was actually judging off the 700mhz version. The PIII 1.4GHz could do up to 2005 IMO, the SSE gives it a little more lifetime to run games like Quake 4, Serious Sam 2, Battlefield 2, Republic Commando and maybe even Half-Life 2 Episode 1. AGP Radeon9x00 of course, considering the Voodoo2/3 would be bottlenecking it down to 2000 again.

Well, Half-Life 2 vanilla with a 6600GT was giving me around 20fps at Medium Details and 1280x1024 if I'm not mistaken which isn't all that playable. I don't imagine Doom III and Quake 4 would be any better.
I'll have to try Far Cry and see how it fares though!

I played on my P3-S 1.4 with a Geforce 6800 vanilla through 2005. But certainly not all maxed out and having constant 20-30 fps, unfortunately. 😀

My Quantum3d Graphite runs a PIII at 733MhZ with a Voodoo 5 5500 (AGP version) for graphics, Windows 2000 Professional. My main problem is it only has 128MB of very slow RAM installed. I could use at least 256 for some of my games. I'm keeping that system strictly for OpenGL/Glide games, though Klingon Academy runs *perfectly* even though it's a DirectX game. It's the first system I've ever had KA run well on in years! Also, Messiah by Shiny Games.

Klingon Academy's an odd CPU hog. It also runs the same on a PCX2 as it does on a Voodoo2.

Another Trek title on myPIII system I tried was New Worlds. On most newer platforms, I always had tiny, corrupted text.

I've been playing with my Tualatin 1.6ghz rig + GF3/ V2 SLI rig the last couple of days, and I would say the answer to this question in 2013 at least, given our own increased expectations and standards, would be 2001. Anything 2002 onwards, I would rather entrust to an Athlon XP/64 or P4 system. For instance, WC3 takes forever to install on my P3 rig.

2004 for me. My 1.59GHz PIII+9800Pro setup handles nearly all of my 2004 games just fine at 1280x960 or 1440x900. I never bother with AA, of course. There's something insanely great about replaying games that used to struggle on my pricey P4-1800/Radeon 9500Pro on a PIII I built for $40...at twice the frame rate. 😀

2005 and newer games go on the 4.6GHz i7.

I agree on 2004,
2005 was already SM3.0, dual core and the preparation for the Xbox 360...
but 2004 was when Doom 3, Far Cry and Half Life 2 were the best, and these games can be played on a fast Pentium 3, obviously a high end CPU from 2004 would do better (Athlon 64)

I'd also say 2004 at best fot he Tualatin 1.4 GHz.

It was a monster of a computer back in the day, I remember quite well the soaring prices of these CPUs on eBay and elsewhere and dozens of enthusiasts keep saying that a P3 1.4 GHz. would hold its own against a 2.0 GHz. P4 in almost any real world scenario. But, for me, a lot of hardware died when Doom 3 was released, even if I have never liked the game itself, but its graphics were absolutely thrilling. My recollection of those years is that no one had ever seen a true DirectX 9 game until Doom 3 (although being an id game it probably uses more OpenGL than DirectX) and that my GeForce4 Ti struggled to move it while the newer Radeon 9700/9800 Pro cards were playing it with more impressive visuals and faster speeds.

Yes, I'd definitely state 2004 as the final year where a P3 Tualatin based gaming rig made sense.