It depends on the game and resolution.
In certain games / certain (lower) resolutions, the P3 450 will be the bottleneck. For other games and higher resolutions the two Voodoo 2s will be the bottleneck.
Two Voodoo 2s in SLI will scale up to an 800 - 900 MHz Coppermine. But these are pretty rare, edge cases. I would say that, generally speaking, the 450 Katmai is a good fit for a Voodoo 2 SLI build.

I keep FPS games at 800x600. GLQuake and Q2 run epically. Q3 runs acceptably with some slowdown when a large area of fog is on screen.

A 600mhz P3 would be nicer.

I would definitely recommend PIII 600. 450 would be ok for a single Voodoo 2. I'm running my PIII 1Ghz downclocked to 750Mhz due to 100Mhz bus - this is also an option for you.

There is also Coppermine Celeron 1Ghz with 100Mhz FSB. There were 800 and 900Mhz versions too. Another option is to buy Coppermine Celeron 566-633 (66 FSB) and overclock it to 100Mhz FSB. If you buy a few of them (they are very cheap, nobody buys Celerons) there is very good chance they will run at 850-950Mhz if your board allows setting 1.75V voltage (standard for 1Ghz PIII).

I'll get a 600 or 700mhz P3 that's meant for 100 FSB. I'm afraid of buying the wrong one to be honest. I've burned myself on more than a few ill-researched components.

The Manual states:

The motherboard supports the Pentium III processor at 450 MHz and 500 MHz with BIOS version
4W4SB0X0.86A.0009.P02 or later. The motherboard supports the Pentium III processor at 550 MHz with
BIOS version 4W4SB0X0.86A.0011.P04 or later. Earlier BIOS versions will identify the processor as a
Pentium II processor and will not work reliably with a Pentium III processor.

Source: http://www.win3x.org/uh19/public/motherboard/ … ce333381416.pdf

A 100Mhz bus Pentium III 600 will most likely also work because it still uses the same core voltage.

Dorunkāku wrote on 2021-10-02, 08:27:

A 100Mhz bus Pentium III 600 will most likely also work because it still uses the same core voltage.

It depends. I have an Amptron motherboard that works fine with Katmai CPUs up to ~ 500 MHz. Anything higher than that results in freezes/instability - probably because of the high power requirements that the high-frequency Katmai CPUs have. The same motherboard also has issues with Klamath 300 MHz CPUs (for the same reason, I'm guessing).

I was interested in a similar option with my Compaq Deskpro EN SFF (BX440) with the original PII 350 Deschutes. Compaq offered the maximum possibility of upgrading PIII 550 Katmai, but the board has VRM 8.4 specs, so I also ran Celeron 900 Coppermine over the slocket reduction, as you can see on the screen. So it depends on what specification the VRM used has and if it is able to deliver the necessary voltage and current. Then, if you're lucky, you'll be able to run a CPU that might not be correctly identified by BIOS, but will run properly.
Of course, it doesn't work on all boards - some simply refuse to run with an officially unsupported CPU.

If it helps with finding info, the PC is a Gateway LPMini-Tower TBR3 450.

AIDA32 claims it can go up to a max of 2.0 core voltage. The P3 600s I'm seeing are listed at 1.65v.

Seems like a straight forward drop-in deal.

EDIT: Found multiple sources saying a P3 600 is not a problem for this machine.

TSG wrote on 2021-10-02, 20:02:

If it helps with finding info, the PC is a Gateway LPMini-Tower TBR3 450. […]
Show full quote

If it helps with finding info, the PC is a Gateway LPMini-Tower TBR3 450.

AIDA32 claims it can go up to a max of 2.0 core voltage. The P3 600s I'm seeing are listed at 1.65v.

Seems like a straight forward drop-in deal.

EDIT: Found multiple sources saying a P3 600 is not a problem for this machine.

With one of the later BIOS revisions (which include the 681 / 683 CPUIDs) you should be good to at least Slot 1 PIII 800MHz cpus (possibly even the 850MHz one as well). Also, the equivalent socket 370 cpus on a suitable sloket will probably work as well. Here's a link to the latest BIOS (revision P14)

https://web.archive.org/web/20040313014622/ht … abor2/vp14.exe#

and the BIOS notes

BIOS support for specific PIII frequencies is often overrated. As long as at least one Coppermine model is supported the rest should work as well. I have Enpc KB21P board and in BIOS there is max 5.5 multiplier but it boots fine with faster Coppermines as the BIOS multiplier setting is ignored.

Fast slot 1 PIII models above 600Mhz are very expensive and I would not recommend buying them from ebay. You will be better off buying socket 370 CPU + slotket (must have jumper for Coppermine).

Even a plain Slot1/PPGA slocket is enough, a simple modification allows the Coppermine CPU to function. One wired connection and insulation of one pin, schematics abound on the internet.

For a Pentium III 600 you need to decide if you want a Katmai (2.05v) or Coppermine (1.65V) model. Not all Slot 1 boards support the newer low voltage Coppermine CPUs. Your board should definitely work with a Katmai 600 MHz, but may not with the Coppermine. You need to check the numbers on the VRM chip to confirm compatibility. 600 MHz is the fastest Katmai available, so if you’re happy with that level of performance, consider buying a Katmai 2.05 V version instead of a 1.65 V Coppermine. You’ll want to look for these markings on the top: 600/512/100/2.05V rather than 600/256/100/1.65V. There are also 133 MHz bus versions of the PIII 600 MHz for both Katmai and Coppermine. These will have a 133 instead of 100 in the model number and may have 600B or 600EB instead of 600. You want to avoid these 133 MHz bus versions since your motherboard does not support it.

I've found a P3 800. Has the usual big aluminum heatsink common on Slot 1 CPUS. Is passive cooling good enough for these? My PC has the plastic shroud over the heatsink/CPU that lets the PSU fan pull heat out.

Is it an 800/100 or 800/133? If it’s the latter it will only run at 600 MHz in your machine due to the 100 MHz FSB limit.

Regarding cooling, Gateway used that cooling shroud design on a bunch of Pentium III Slot 1 machines. The 450-500 had just a passive heatsink. The 550 and 600 Katmai had a small fan added to the center of the heatsink to handle the extra heat. The 500 has a TDP of 28 W and the 550
has a TDP of 30.8 W. So right around there should be the limit of the Gateway cooling shroud + PSU fan setup. The 800/100 PIII has a TDP of 20.8 W. So you should be totally fine with a passive heatsink as long as it fits under the original shroud.

Now you just need to confirm if it’s an 800/100 or 800/133 model and if your board supports Coppermine CPUs.

I run a 1GHZ PIII with my Voodoo 3. Might be overkill, but not by much.
I wouldn't worry too much though, I also run a V3 with my K6-3+ at 500mhz and that is definitely a bottleneck.
If it plays the games you enjoy then upgrade when you get a good price.

Edit: I also have a Compaq Deskpro that came with a a Katmai at 450mhz. I upgraded that machine to a 700mhz Coppermine with zero troubles at all, and I don't think that it was officially supported at all.

Katmai500 wrote on 2021-10-04, 14:41:

Is it an 800/100 or 800/133? If it’s the latter it will only run at 600 MHz in your machine due to the 100 MHz FSB limit. […]
Show full quote

Is it an 800/100 or 800/133? If it’s the latter it will only run at 600 MHz in your machine due to the 100 MHz FSB limit.

Regarding cooling, Gateway used that cooling shroud design on a bunch of Pentium III Slot 1 machines. The 450-500 had just a passive heatsink. The 550 and 600 Katmai had a small fan added to the center of the heatsink to handle the extra heat. The 500 has a TDP of 28 W and the 550
has a TDP of 30.8 W. So right around there should be the limit of the Gateway cooling shroud + PSU fan setup. The 800/100 PIII has a TDP of 20.8 W. So you should be totally fine with a passive heatsink as long as it fits under the original shroud.

Now you just need to confirm if it’s an 800/100 or 800/133 model and if your board supports Coppermine CPUs.

It's the 100 FSB one and I've updated the BIOS to support the faster P3s up to 800mhz officially.

BX boards will usually allow you to push up the FSB speed beyond 100MHz either through bios or jumpers (depending on motherboard) and/or through softfsb.exe - Can usually clock up 103, 112 and 133MHz - you overclock the AGP bus as you do so, as ever, how close to 133MHz you will manage will vary (and you'll likely need PC133 RAM rather than PC100 if you havent already).

So if you have a native 100MHz FSB chip, be worth trying a spot of overclocking (my p3 450MHz slot one CPU ran ok at 112MHz FSB but system instantly crashes if push to 133 in softfsb), or if you do buy a 133 FSB chip, you may lose a bit less speed that those above suggest (or none if your system is stable at the full 133MHz)

TSG wrote on 2021-10-04, 06:02:

I've found a P3 800. Has the usual big aluminum heatsink common on Slot 1 CPUS. Is passive cooling good enough for these? My PC has the plastic shroud over the heatsink/CPU that lets the PSU fan pull heat out.

You should be fine, but the PSU will suffer... If you want to use that computer, I think you better remove that shroud and install a big (12 cm or more) fan near to blow from the side.

Success!