Hello,
Are they the exact same model ?

Indeed, in many cases, the same model of cards must be exactly the same (because of the personal signed eeprom by the manufacturer / dealer brand / drivers).
I had this problem by putting a Creative Labs with a Diamond (physically the same model yet).
It seems that there are mixed drivers, somewhere, but at the time I had not gone that far.

Does the system work with a single Voodoo 2 card installed? DirectX 7.0a should not pose a problem. Moving the cards around into different PCI slots might help - it's worth a shot, but don't get your hopes up. Voodoo2 cards will work even in slave PCI slots.

I had similar issues as yours a few weeks ago with 2 different 440BX motherboards (and 1 Via). Moving the SLI setup to a SiS XP4 chipset solved the problem for me, but still doesn't seem like it should be necessary (in my mind). What I tested was documented in my thread below:

[SOLVED] 2 sets of SLI Voodoo2 Cards on 2 440BX Chipset-equipped Motherboards Blackout & System Locks up when 3D Engaged

Romain wrote on 2022-02-22, 13:18:

Indeed, in many cases, the same model of cards must be exactly the same (because of the personal signed eeprom by the manufacturer / dealer brand / drivers).

The way this is implemented is by a series of strap resistors to mark the board manufacturer - there's no eeprom. There are drivers which are patched to have this comparison removed - the "FastVoodoo" drivers support this:
https://dbzer.net/FalconFly/voodoo2.htm

The few times I've had issues with Voodoo2 SLI in different machines, it was because of the power supply I was using not being beefy enough for all of the cards I had in the machine - once was with a Dolch portable where the built in PSU just wasn't up to snuff (it turned out to be failing), and another was when I tried to use a PicoPSU. I'm not suggesting using today's version of a beefy power supply (350W is probably fine) but it's something to look at.

Romain wrote on 2022-02-22, 13:18:

Hello, Are they the exact same model ? […]
Show full quote

Hello,
Are they the exact same model ?

Indeed, in many cases, the same model of cards must be exactly the same (because of the personal signed eeprom by the manufacturer / dealer brand / drivers).
I had this problem by putting a Creative Labs with a Diamond (physically the same model yet).
It seems that there are mixed drivers, somewhere, but at the time I had not gone that far.

They are the exact same make/model from what i can see, apart from a slightly different colour soldermask they are the same. I did not purchase them together, i only got one of them recently but have had the other for some time.

A mismatch doesn't make sense if the setup is working in the motorhead demo and 3dmarks.

Meatball wrote on 2022-02-22, 14:42:

Does the system work with a single Voodoo 2 card installed? DirectX 7.0a should not pose a problem. Moving the cards around into different PCI slots might help - it's worth a shot, but don't get your hopes up. Voodoo2 cards will work even in slave PCI slots.

The system 'works' right now for the motorhead demo and the 3dmark tests - just not in actual games. I removed one of the v2 cards a while ago to sanity check and i got the same results, works in demos/marks but not in-game. I might have to retry that though on my next teardown -this could eliminate potential power supply issues perhaps. I don't want to have to change the motherboard here but if i'm going to be tearing into the system, i have another Dell dimension xps 300 i could test them in - i think its basically the same motherboard however.

I had converted the motherboard currently in use from being Dell-PSU only ATX connector to use a regular ATX PSU by moving the connector along, and the old AT power connector goes unconnected. Its a long shot (as its mainly for 3.3v use) but i could investigate powering the additional connector perhaps.

All of that doesn't explain why it can work with SLI enabled (or disabled) in the 3dmark and motorhead demos. This is why i posted here in 'software' because it still feels like a configuration issue?

andysarcade wrote on 2022-02-22, 15:29:

They are the exact same make/model from what i can see, apart from a slightly different colour soldermask they are the same.

Wrong.
One has 100MHz RAM, the other 90MHz.

RaiderOfLostVoodoo wrote on 2022-02-22, 15:46:

andysarcade wrote on 2022-02-22, 15:29:

They are the exact same make/model from what i can see, apart from a slightly different colour soldermask they are the same.

Wrong.
One has 100MHz RAM, the other 90MHz.

Ok, so I appear to have missed that pretty glaring fact (doh!).

So would this be considered enough of a difference between cards to break compatibility, considering they have demonstrated they do work together in demos? USing the 'mismatch' driver fast 4.6?

I physically pulled one of the cards out just now, I get the same results, demos ok, games not so.

Reinstall Windows with just 1 voodoo card and use 3.02.02 reference drivers. There should not be any need to update DirectX since 98 SE is DirectX 6.1 (but please doublecheck if my memory has failed me). You'll likely be fine if you really want to update to DirectX 7.0a. You won't be able to run 3dmark 2000 without this version, of course.

If all is well, add the 2nd and test again.

Maybe a trick for you here : Re: Dell XPS, Half Life 1, TNT1 confusion

"having to copy 3dfxgl.dll to opengl32.dll"

Romain wrote on 2022-02-22, 23:53:

Maybe a trick for you here : Re: Dell XPS, Half Life 1, TNT1 confusion

"having to copy 3dfxgl.dll to opengl32.dll"

After re-installing windows 98se onto another drive and setup, and finding the same results, i read your response and then looked at the thread linked and others, and it finally worked when the driver was copied and regular opengl was selected, finally! It appears to work in SLI and regular mode too!

Thanks for your help, at least this is a sanity check fix. Now i need to work out why other games refuse to work properly.

Yeah, reading the OPs post, everything seems alright.

OpenGL games will either require that you use a driver with a full OpenGL ICD or that you use miniGL and drop the .dll in the appropriate folder for each game.

The other three games that you mentioned are DOS 3Dfx games and can be a bit more finicky. In all cases, you need the appropriate patch, either a specific Voodoo2 or Voodoo Rush as you've done for Tomb Raider and you need to drop glide2x.ovl from your driver folder to the game's folder where the executable is. This is the library that tells the executable how to interface with your card. I'm sure doing this will solve most if not all your games not running. All of them are finicky though.

If you want to test Direct3D (DirectX 7.0 is fine by the way, don't go above that) beyond 3DMark, just try a D3D game. Tomb Raider 2-4 should run fine on the Voodoo2 and they have a nice config tool allowing you to select the card you want to use and such. I recommend uninstalling the FastVoodoo2 drivers and instead using the latest reference drivers. FastVoodoo2 overclocks the cards slightly IIRC and you may not wish that, it would not make any difference with a Pentium II 450 anyway.

Garrett W wrote on 2022-02-23, 07:45:

Yeah, reading the OPs post, everything seems alright. […]
Show full quote

Yeah, reading the OPs post, everything seems alright.

OpenGL games will either require that you use a driver with a full OpenGL ICD or that you use miniGL and drop the .dll in the appropriate folder for each game.

The other three games that you mentioned are DOS 3Dfx games and can be a bit more finicky. In all cases, you need the appropriate patch, either a specific Voodoo2 or Voodoo Rush as you've done for Tomb Raider and you need to drop glide2x.ovl from your driver folder to the game's folder where the executable is. This is the library that tells the executable how to interface with your card. I'm sure doing this will solve most if not all your games not running. All of them are finicky though.

If you want to test Direct3D (DirectX 7.0 is fine by the way, don't go above that) beyond 3DMark, just try a D3D game. Tomb Raider 2-4 should run fine on the Voodoo2 and they have a nice config tool allowing you to select the card you want to use and such. I recommend uninstalling the FastVoodoo2 drivers and instead using the latest reference drivers. FastVoodoo2 overclocks the cards slightly IIRC and you may not wish that, it would not make any difference with a Pentium II 450 anyway.

Thanks for the pointers! I guess i went for the games i really wanted to see that i remember first from back in the day, not realising they are indeed fussy as heck. I took your suggestion and have a Tomb Raider II demo disc here (i thought it was the full version until now i see its just a demo!) and installed that, under win98 it detects, tests, and plays absolutely fine in SLI.

I guess i need to work on the dos 3dfx games a bit more, right now dropping to dos mode i can get tomb raider running 3dfx, but with a loss of blue maybe and screen has massive purple interference, very strange.

I shall perservere with the other games, I guess i needed to be reminded of the 'dropping the driver in the game folder' trick.

The fastvoodoo.it 4.6 drivers can have the speed set to normal (85) from their standard overclock speed in the tab, for elimination of problems i did this from the start anyhow. I have mixed and matched with the other reference drivers, and now with the games that work, they don't mind any of the drivers loaded it seems.

It would be great if the half-life Blueshift screen doesn't go black everytime you go out to the menu and then try to drop back into the game :\ have not found a solution to that yet!

andysarcade wrote on 2022-02-23, 16:03:

Thanks for the pointers! I guess i went for the games i really wanted to see that i remember first from back in the day, not rea […]
Show full quote

Thanks for the pointers! I guess i went for the games i really wanted to see that i remember first from back in the day, not realising they are indeed fussy as heck. I took your suggestion and have a Tomb Raider II demo disc here (i thought it was the full version until now i see its just a demo!) and installed that, under win98 it detects, tests, and plays absolutely fine in SLI.

I guess i need to work on the dos 3dfx games a bit more, right now dropping to dos mode i can get tomb raider running 3dfx, but with a loss of blue maybe and screen has massive purple interference, very strange.

I shall perservere with the other games, I guess i needed to be reminded of the 'dropping the driver in the game folder' trick.

The fastvoodoo.it 4.6 drivers can have the speed set to normal (85) from their standard overclock speed in the tab, for elimination of problems i did this from the start anyhow. I have mixed and matched with the other reference drivers, and now with the games that work, they don't mind any of the drivers loaded it seems.

It would be great if the half-life Blueshift screen doesn't go black everytime you go out to the menu and then try to drop back into the game :\ have not found a solution to that yet!

The issue you're facing with Tomb Raider is a classic one. I can't recall how you can go about fixing it, but you can search on VOGONS to find out more. I forgot to mention that there was a batch file you were supposed to run prior to running any of the DOS 3Dfx-enabled games, as they typically expected a Voodoo 1 and didn't entirely know what to do with newer cards (even the Voodoo Rush!). There are some games even that will only run on Voodoo 1 even! This might be a good place to start learning more about the subject.

As for the fastvoodoo drivers, there might be other tweaks under the hood or hidden within .ini files and registry entries that are better suited towards newer games. There was something of a, unhealthy almost, fascination surrounding 3Dfx hardware that lasted for many years, people with a strong sense of pride in their ownership of said hardware, lack of knowledge surrounding graphic features and APIs and general unwillingness to "give up to the enemy" (i.e. Nvidia), that kept on running them for many years past their prime. Regrettably, as you can imagine, this led to annoying fanboy-isms and misinformation being spread around, but it also led to some undoubtedly cool-as-shit stuff such as people running Doom 3 with their Voodoo2 SLI systems, writing drivers for NT5.0 OSes, making sure modern games ran to some degree on their aging cards.
FastVoodoo2 is very much a case of the latter, people tweaking drivers to run games from 2003-2004 on their Voodoo2 cards. The tweaks ranged from simple, such as applying a safe overclock to the cards to boost performance and forcing Vsync off, to replacing OpenGL ICDs with more recent and perhaps full-featured such as MesaFX, as well as adding support for DirectX releases beyond 7.0a thus tricking games into running despite there being no official support for the video cards among many other tweaks.

As such, you might run into weird issues with older games. These drivers are meant to run newer games on faster systems. Think Athlon XP and Pentium 4. They do have cool wallpapers though! You will probably have an easier time with the latest reference drivers, especially considering you have a matched SLI pair.

In any case there doesn't seem to be anything wrong with your cards 😀.