I've used those tie-ribs (small metal wires covered in plastic) before to mount fans on stock heatsinks of AGP Geforce 6 cards before, though those cards have much larger heatsinks. It's worked perfectly for as long as I used that computer regularly.
I'm not a fan of using glue though others on Vogons have found that to be a good solution. I don't like it since it's sorta permanent 😜
One thing you could try is to mount a (small) CPU HS cooling fan on the Voodoo's HS using screws (though that leaves traces and scratches on the Voodoo's heatsink) though I've personally never done that on a Voodoo.

Some AT cases have the option of putting a fan behind the front bezel so it gives 'some' cooling to the expansion cards, though I'll assume yours doesn't have that option.

Btw, those Voodoo 3's always tend to get quite hot so that's not that abnormal.

Whats the rest of your system btw?

I'd mount a fan on the stock heatsink, if you have the space for it. Simple and effective.

I'm guessing screws don't fit on a 3000 because the fins are too far apart. Two options:
- Hot glue. Not pretty, but easy enough to get off should the need arise.
- Drill small holes in the heatsink and use zip-ties.

You're from Germany, right? pollin.de has cheap 40 and 50mm fans.

Addition: You can see a picture of how I mounted a case fan using tie ribs on a Geforce 6800 in this post (scroll down a bit to see a thumb of the pic)
New rigs! (first ones of a bunch)

dr.zeissler wrote:

The card get's very hot and the small AT-Case has no Option of getting the Card in an airflow.

Voodoo3 does not care, don't bother.

The heat-sink as such is pretty decent, but the lack of airflow is the real issue. I just put a 120 mm fan next to it and that takes care of business. The back doesn't have to be cooled when the front gets airflow, at least this is my experience.

I think I should mount a fan nearby the V3, but how can this be done. Any ideas what material should be used to mount the Fan on it and to place it nearby ?
Perhaps I should get a PCI-Fan-Card and mount the PS/2 Mouseport on it?

This is what I did, I had a spare Zalman PCI Mounting bracket (Was meant for their Flower cooler)

This is cooling a Voodoo 3 2000 PCI with the even smaller heatsink. I can't touch the heatsink for a second without burning myself without it. Attached is a 92mm which is running at 7v.

Thank You!!
This is exactly what I am searching for.

I ordered one in israel (ebay)
Expecting to get in in nov-2014.

Thx!

Check out this thread:

Oops, I think I killed my Voodoo3