Memory from Matrox G400 cards should be compatible, I already did a few attempts but I find it very tricky. That's because of lack of soldering experience of course. 😉
Don't forget to relocate the tiny resistors after you succesfully replaced the VRAM.
My next try will succeed! 😜

Just done the mod on my 6168 revision 2 board. In my case I used an Ati Rage Pro Turbo 16MB with 4x SGRAM chips - the Samsung K4G323222A-PC60 chips. They're 512k x 32-bit x 2-banks for 32 megabits or 4 megabytes per chip. Essentially, any SGRAM with similar voltage and address line configuration should work - the higher density memory adds an A10 line alongside the bank select, on pin 45.

Taking it from the ATI card meant I could test the RAM while it was on that card too 😀

For the chip removal from the donor card it had a flat back so I was able to pre-heat the back side and bring in hot air from the top to get the QFP memory chips off quickly with no hassle. For removal of the original chips from my board I used low-melt solder for the SGRAM by the memory slot because hot air there would melt the slots. The rest of the RAM chips I removed first of all by putting kapton tape on the side edge of the Voodoo 3 chip to stop hot air going under there, then put tin-foil over anything I didn't want to get heated. The new memory was resoldered by hand and I'm out of good flux so it was tough.

This thread documents it nicely visually: https://www.voodooalert.de/board/forum/index. … en-ursachen%2F=
And there's a write-up on what specifically needs changing here: https://3dfx-alive.de/3dfx-mainboards

I think it may have originated from here - https://imgur.com/gallery/LAt1McR and the video: https://www.youtube.com/watch?v=wC40KY_e6K8
In the video he's using the same memory you're planning to use so it's confirmed to work, but the video has some red herrings and no close up pictures so that's more for background info than to directly try to follow.

The resistors by the memory / southbridge need to be moved / added to, I used a blob of solder on cut resistor legs since those are 0-ohm resistors. But now that I've finished it I'll say that it's best to first get the new RAM installed and confirm it works exactly as the original memory did before trying to go up to 16MB. I had solder bridges all over which lead to lines, flashing blocks, etc.

And VMTCE doesn't work with its default settings on this board so I had to count lines on the screen to figure out which bits were shorted - for reference if you have to do that, boot into windows on the broken display video card and set the video mode to 640x480 & 256 colours. Then take a screenshot that shows the bit errors and count pixels. I had errors on the 2nd line of pixels which meant there was a short on the DQ9 to DQ15 pins of the first memory chip, which is by the memory slots.

Also, I was flummoxed for a bit because the computer booted once at 16MB after completing the modification and all subsequent boots were 8MB - that turned out to be one end of the tiny 4.7k strap resistor had broken off so I sourced one from a scrap board and now it's good detecting 16MB and working again.

Thermalwrong wrote on 2023-12-14, 15:34:

Just done the mod on my 6168 revision 2 board. In my case I used an Ati Rage Pro Turbo 16MB with 4x SGRAM chips - the Samsung K4 […]
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Just done the mod on my 6168 revision 2 board. In my case I used an Ati Rage Pro Turbo 16MB with 4x SGRAM chips - the Samsung K4G323222A-PC60 chips. They're 512k x 32-bit x 2-banks for 32 megabits or 4 megabytes per chip. Essentially, any SGRAM with similar voltage and address line configuration should work - the higher density memory adds an A10 line alongside the bank select, on pin 45.
IMG_2761 (Custom).JPG
Taking it from the ATI card meant I could test the RAM while it was on that card too 😀
IMG_2764 (Custom).JPG
For the chip removal from the donor card it had a flat back so I was able to pre-heat the back side and bring in hot air from the top to get the QFP memory chips off quickly with no hassle. For removal of the original chips from my board I used low-melt solder for the SGRAM by the memory slot because hot air there would melt the slots. The rest of the RAM chips I removed first of all by putting kapton tape on the side edge of the Voodoo 3 chip to stop hot air going under there, then put tin-foil over anything I didn't want to get heated. The new memory was resoldered by hand and I'm out of good flux so it was tough.

This thread documents it nicely visually: https://www.voodooalert.de/board/forum/index. … en-ursachen%2F=
And there's a write-up on what specifically needs changing here: https://3dfx-alive.de/3dfx-mainboards

I think it may have originated from here - https://imgur.com/gallery/LAt1McR and the video: https://www.youtube.com/watch?v=wC40KY_e6K8
In the video he's using the same memory you're planning to use so it's confirmed to work, but the video has some red herrings and no close up pictures so that's more for background info than to directly try to follow.

The resistors by the memory / southbridge need to be moved / added to, I used a blob of solder on cut resistor legs since those are 0-ohm resistors. But now that I've finished it I'll say that it's best to first get the new RAM installed and confirm it works exactly as the original memory did before trying to go up to 16MB. I had solder bridges all over which lead to lines, flashing blocks, etc.
6168-16mb-resistors (Custom) (1).JPG

And VMTCE doesn't work with its default settings on this board so I had to count lines on the screen to figure out which bits were shorted - for reference if you have to do that, boot into windows on the broken display video card and set the video mode to 640x480 & 256 colours. Then take a screenshot that shows the bit errors and count pixels. I had errors on the 2nd line of pixels which meant there was a short on the DQ9 to DQ15 pins of the first memory chip, which is by the memory slots.

Also, I was flummoxed for a bit because the computer booted once at 16MB after completing the modification and all subsequent boots were 8MB - that turned out to be one end of the tiny 4.7k strap resistor had broken off so I sourced one from a scrap board and now it's good detecting 16MB and working again.

Wow, what a great summary!
Thank you for all the details and references and also the tips regarding troubleshooting.

I just ordered 4x K4G323222A-PC60 that should be NOS, so fingers crossed that they really are, and working 😀
I think that soldering the new memory chips will probably be my biggest concern(if I don't manage to fry anything while removing the old once that is) 😁

PD2JK wrote on 2023-12-13, 20:22:

Memory from Matrox G400 cards should be compatible, I already did a few attempts but I find it very tricky. That's because of lack of soldering experience of course. 😉
Don't forget to relocate the tiny resistors after you succesfully replaced the VRAM.
My next try will succeed! 😜

I'm sure you'll manage next try! 😀
Are you struggling with soldering bridges when soldering the new memory chips?

nizce wrote on 2023-12-14, 21:48:

PD2JK wrote on 2023-12-13, 20:22:

Memory from Matrox G400 cards should be compatible, I already did a few attempts but I find it very tricky. That's because of lack of soldering experience of course. 😉
Don't forget to relocate the tiny resistors after you succesfully replaced the VRAM.
My next try will succeed! 😜

I'm sure you'll manage next try! 😀
Are you struggling with soldering bridges when soldering the new memory chips?

There are 400 pins in total to solder and they're quite fine pitch, not easy to spot all the mistakes which is something I really struggle with as well. There's some stuff I can only spot during daylight hours or under the microscope and since the pins are such fine pitch, sometimes there are solder bridges between pins but hidden behind the pins or underneath flux, very tough to spot. If I was soldering enough I'd probably move over to using solder paste but that stuff always goes off before I can use much of it.
Probably the best method is pre-load the solder pads on the board with fresh & even amounts of solder, then apply flux and press the chips down to solder them with hot air. Given the trouble that hand-soldering all those pins gave me it's probably easier overall, but the proximity to BGA chips and plastic sockets makes it a tough decision to make.