Does the card have mounting holes for pins to hold the heatsink on, or is it one of the models that has no mounting holes?

I have thought about this myself and I would probably opt for some moderately sized modern heatsink that would allow for a standard 60mm low profile fan to be attached. If at all possible I would recommend a mounting method that does not involve using permanent epoxy or thermal adhesive to attach the cooler to the card... simply because I don't like making such drastic permanent modifications to cards like these. It is worth mentioning that Voodoo cards just have a plastic package to attach the heatsink to, so having a perfect thermal interface between the chip and cooler doesn't really make much difference. It matters much more that the cooler has enough mass to absorb some heat and enough surface area (fins) and air flow to keep it cool.

Hello,
Below is the picture of the actual card. It seems like having mounting holes:

The mounting holes on those cards have a spacing no other cards used. You have to mod some heatsinks to match the spacing but it's usually no problem.
The crystal left of the main chip will collide with larger heatsinks. The main chip is also close to the AGP slot meaning larger coolers will collide with the slot and need to be filed down a bit.
The Titan TTC-CUV1AB(DIY) is a nice solution because it fits without modifications if you angle the clips a bit but it's somewhat noisy @12V. The larger heatsinks produced by Titan using the same retention clips fit the holes as well but need to be modified so they don't collide with the crystal or the AGP slot.

What about using thermal pads that add a bit of thickness so it will clear nearby components? Normally you want as little thermal interface material between the heatsink and the chip as possible, but since the plastic chip packages on these cards have such poor thermal conductivity, I wonder if the gains of using a larger heatsink would be worth it in the end. The card would run at a lower temperature (less stress over time) and the fan could be quieter and easy to replace.

I have some cards I could try this on at some point. Maybe I will make a project out of this... just not sure what kind of heatsinks I have on hand.

EDIT: Welp... maybe I won't do this just yet. All of the Voodoo 3 cards I have without heatsinks are also ones that have defects I haven't been able to sort out. I suspect that two of them need a reflow but I've never attempted that on a V3 and I'm not sure if I could get it to work without ruining anything.

Ozzuneoj wrote on 2023-01-11, 06:26:

What about using thermal pads that add a bit of thickness so it will clear nearby components? Normally you want as little thermal interface material between the heatsink and the chip as possible, but since the plastic chip packages on these cards have such poor thermal conductivity, I wonder if the gains of using a larger heatsink would be worth it in the end. The card would run at a lower temperature (less stress over time) and the fan could be quieter and easy to replace.

I do not think this is a good idea. It would be much better to use a copper spacer instead of a thick thermal pad which still has rather low thermal conductivity.
Thermal pads are better than an air gap but that's about it.

Doornkaat wrote on 2023-01-11, 07:11:

Ozzuneoj wrote on 2023-01-11, 06:26:

What about using thermal pads that add a bit of thickness so it will clear nearby components? Normally you want as little thermal interface material between the heatsink and the chip as possible, but since the plastic chip packages on these cards have such poor thermal conductivity, I wonder if the gains of using a larger heatsink would be worth it in the end. The card would run at a lower temperature (less stress over time) and the fan could be quieter and easy to replace.

I do not think this is a good idea. It would be much better to use a copper spacer instead of a thick thermal pad which still has rather low thermal conductivity.
Thermal pads are better than an air gap but that's about it.

Yeah, a copper spacer would be best, I'd just be concerned about keeping it in place.

Maybe the best thing would be to find a heatsink that is larger but has a smaller contact area.

.... ohhh... what about using a heatpipe + fan from a laptop? That'd be pretty insane if there was a way to make one of those work, and maybe 3dfx's screwy mounting hole pattern would match that of some laptop socket... 🤣

This comes up every now and then. Do a search on the forum, there are several solutions available.

My personal favorite is a PCI fan bracket since it doesn't require you to mod the Voodoo card in any way.

Joseph_Joestar wrote on 2023-01-11, 07:42:

My personal favorite is a PCI fan bracket since it doesn't require you to mod the Voodoo card in any way.

Yes. If you can spare the space in your PC, this is by far the quietest and most long-lasting way to do it, but only if the card already has a heatsink on it.

I think I posted in another thread somewhat recently about some brackets that can be used to attach a 90mm fan to a plate that screws in like a PCI card.

Ozzuneoj wrote on 2023-01-11, 07:45:

I think I posted in another thread somewhat recently about some brackets that can be used to attach a 90mm fan to a plate that screws in like a PCI card.

I use one of those with a Noctua 92mm fan.

Usually, they are mounted horizontally, just below the card. But some can be used vertically as well, and don't take up any extra space. Mine is like that, and you can see a pic at the bottom of this post. Technically, you could even mount 120mm or even 140mm fans on these.

I've successfully restored some Voodoo 3 3000 cards using a 60 x 45 x 18mm heatsink from this ebay seller and a 30mm x 5m double sided thermal adhesive tape from this seller (no affiliation with either of them).
The heatsink is very similar to the original one and the adhesive tape has a very good thermal transfer. Overall, the cooler behaves better than the original heatsink + thermal glue. With a bit of airflow, the temperature measured on the card's back (right behind the GPU) after a 1h stress test did not exceed 55 degrees C, which is very good.

This is how the card looks like:

Joseph_Joestar wrote on 2023-01-11, 07:42:

My personal favorite is a PCI fan bracket since it doesn't require you to mod the Voodoo card in any way.

This is what I do. I have a flaky Voodoo2 that malfunctions when it overheats. This solved the problem.

ETA: I bought a bunch of these things and fit them to nearly all my computers:

https://www.aliexpress.com/item/4000848479968.html

Thanks for the details bloodem. I believe the V3 2000 heatsink is only around 40mm. I found a 40x40 mm heatsink locally. Also the locally available thermal tape has only 10mm width.

Is there any cooling penalty in using a 40x40x20 mm heatsink for the V3 3000 with a 10mm tape Strips pasted side by side ?

This is what I did.

I think you can go reasonably insane with Zalman ZM80A-HP cooler.

appiah4 wrote on 2023-01-28, 15:26:

This is what I did.

Looks good. How did you manage to attach the heatsink to the board?

stealthjoe wrote on 2023-01-28, 16:40:

appiah4 wrote on 2023-01-28, 15:26:

This is what I did.

Looks good. How did you manage to attach the heatsink to the board?

3M thermal double sided tape.

Recently attached a fan to the custom heatsink (which is attached to the main IC with a double sided thermal tape). Kept the fan as an intake (blowing into the heatsink).

After switching on the board, a few minutes later noted that the area at the backside of the main IC was quite hot (not sure of the temp but could be around 60-65 deg C) and the heatsink was cold. Trying to understand if this fan placement is correct or whether it should be placed as an exhaust (blowing away from the heatsink). Was searching for many answers, but there seems to be a lot of debate around this. From a Voodoo 3 perspective, could someone please share their experience on using an active cooling? Thanks!

A while back I did a bunch of research on different thermal tape. It is basically all trash. I even contacted a company that manufactures it for industrial use. It wasn't any better than the super cheap crappy junk.
You are not going to get anywhere near the heat transfer you will with half-decent thermal compound.

The company that makes Arctic Silver 5 used to make a thermal epoxy, but they stopped quite a few years ago. There really isn't anything available anymore that is even remotely close to it.

Had initially wanted to use a thermal paste, but alas was having a tough time finding a heatsink fan combo compatible with the board holes. Also didn't want to go with a thermal adhesive for obvious reasons. So thought of going with a heatsink (40x40x20mm) with a pre-applied thermal tape. TBH, the tape was indeed working. Was able to feel bulk of the heat getting transferred to the heatsink. The experience was quite similar to the original heatsink. This was prior to attaching the fan.