Just to be sure - you do know that frequency has _zero_ influence on the speed of VGA graphics in DOS? and maybe couple percent in 2D windows? It might have bigger impact on "accelerated" 3D, but 3D on this chipset is a joke.

The memory clock having zero influence on DOS VGA speed isn't exactly true. When DOS applications write to memory, they write to a FIFO, and that FIFO gets flushed to memory (possibly using page-mode "burst" access) while the software continues running. At 50MHz memory clock, the S3 Virge DX is fast enough flushing the FIFO that in most applications the memory speed doesn't matter. But certain use cases (like randomly accessing memory, or just running a REP STOSD without doing anything else) can detect a difference in memory clock. Most prominent is reading from video memory, as reads can not be buffered and processed in the background. Reading video memory is so slow on most SVGA cards that nearly no performance-critical application is relying on it, but the performance difference (measureable with low-level memory benchmark tools) is definitely there.

egbertjan wrote on 2023-08-24, 02:55:

Can I exchange bios chips from different s3 virge dx cards? [...] The memory has 60 nano and it runs at 50mhz.

What a waste of a perfectly good Virge/DX chip. That's the recommended timing for entry-level Virge (no DX) cards. The Virge/DX has slightly better 3D performance/MHz, but running the Virge/DX 3D engine at 50 MHz is as sensible as running a 486DX with its internal cache disabled. Some people might argue that running the Virge/DX 3D engine at all is pointless. For Terminal Velocity, one of the best known S3D games, my experience is that gameplay started to be enjoyable (for me, that is consistently above 10fps) on a Virge/DX clocked at 70MHz, with biliear filtering and perspective correction disabled. But if you really want to enjoy terminal velocity, just get a Pentium 166, enough RAM for the high-res textures (hint: The Virge/DX requires textures in video memory, Terminal Velocity only uses 2MB, even on 4MB Virge cards, and there is not enough space for high-res textures) and use the standard software renderer.

Can I swap bios chips between the cards without breaking the cards or should I just try it out and see if it works?

I think it's unlikely you'd break the card. If it was me and the EPROMS were the same pinout, I'd just swap it in and see if it POSTS.

Only thing I'd watch for is if you are using a much older CRT, plug it into the VGA port and if you don't get a picture unplug it quickly: just on the 10000000:1 chance that the card outputs some odd frequency the monitor doesn't like. I think that's as likely as me giving birth to a live Zebra, but best to cover all the angles!! 🤣

You can try if the BIOS will work with other card without any physical interventions/swapping of the BIOS chips. Just dump the BIOS with NSSI.EXE and then shadow-load it while using another card with VGABIOS.EXE (VGABIOS loader from nVidia). This method was tested by me and works for S3 ViRGE cards.

I now tried some BIOS-chips on other S3 Virge DX-cards and it worked very well, so this was a succesfull experiment.