I just got an old Voodoo3, and it's a nice graphics adapter, but the rest of the machine (K6-2, 400 Mhz) cannot decode Mpeg-2 fluently. Then, I read that the Voodoo3 itself should be able to decode up to 30 frames fluently without problems.
However, it doesn't work with me, even when using the old PowerDVD 4 (heard that this one would support the Voodoo3, 16MB).
I'm using the AmigaMerlin-Drivers under WinME.
DirectX 9.0c is installed.
Hardware-Acceleration in PowerDVD is activated.
I cannot use WinXP due to an old ISA-SoundCard (no drivers).
Should I use other drivers or another MPEG-Decoder?
Because there is no speed difference between Hardware-Acceleration enabled or disabled, and it just doesn't work fluently...

sounds like powerplay 4 is the issue here. It requires a more processing power than a k-6 400 for no logical reason. If it is a vcd download a vcd player from the net. If it is just an mpeg2 file use windows media player. If it is encoded in something besides mpeg2 search the net for old video codecs

...that... and overclock that K6-2 to at least 500Mhz, if not 550Mhz  with jumpers; and then - it should go fluently. I had a system like that some 8-9 years ago ;) You could get a new heatsink that should have no problems cooling that CPU @ 550Mhz.

Place the jumpers to 5.5 x 100Mhz... Good luck  8)

If the Hardware acceleration of the DVD Software is enabled, it should work, but maybe not at 100% efficiency, resulting in the effect that you are describing.

A good working MEPG-2 Hardware decoder (the Voodoo3 is no 100% hardware supporting decoder, but has a number of useful assisting decoding features) should massively improve performance if enabled.

3rd party Drivers were always optimized and tailored for Gaming, so I see a chance that the Drivers may not be the best solution for MPEG-2 Decoding.

May or may not help, but I'd try a stock 3dfx reference Driver for a test. I see a small chance that it may improve the playback performance.

Otherwise, make sure no post-processing effects are enabled in the DVD Software. Many modern DVD Players have fairly high minimum CPU requirements, because they have internal Post-Processing routines enabled by default (which might not be accessible from the Preferences Menu at all)

In that case, using an older Version or another Player (ideally from the old days, 1999 to 2001) might be the best overall solution.

I believe I had WinDVD in the old days, working with Voodoo3 and later Voodoo5. As far as I remember, that worked just fine with a K6-2 500 at an acceptable CPU load.

Overclocking usually does not help here, because the K6-2 does not gain alot from it (its FPU lacks performance primarily by design, not by clockrate). Going from 400 to 500 (or even more) puts the CPU, Motherboard voltage regulators and Cooling setup at a high risk of failure.
I lost two K6-2 Systems (catastrophic failures, resulting in total losses) in the old days.

I have P3 800MHz and Voodoo3 3000 16mb

and movies run well with VLC player <-try that its very good program. It is able to show all video formats

At the time of 3dfx's demise, many U.S. boxed Voodoo3-Voodoo5 cards had mail-in offers that could be used to get copies of WinDVD 2000 if the owner was willing to pay about $4.00US shipping.

WinDVD 2000 pre-dates PowerDVD 4 a bit if memory serves.

First of all, I have to express my thanks, I would not have thought that so many people are still interested in 3DFX-Cards.
I have already tried the original driver, it didn't help, though I have not tried WinDVD (yet). VLC is much slower, and somehow, the OpenGL-Output doesn't work there (don't ask me why!).
The interesting thing is, when I overclocked at 450 MHz (didn't want to risk more), it did NOT become more fluently - however, when I disabled the sound, it ran mostly smoothly. CPU-Load then was something about 80% - 90%.
Maybe, it's a sound-acceleration-problem, too, because in VLC, the sound only is garbage (it seems to play the audio of normal MP3's two times at the same time!) and in PowerDVD, I can neither mute nor adjust the volume (it always shows 0%, though the Windows mixer works normally). I use an old ISA-Card from Miro (Miro Sound FM 10), but maybe I'll try to change that because that seems to be the real problem.
I already disabled all postprocessing in PowerDVD (and VLC), though deinterlacing stays active all the time.
The fact that the speed is not much different when using the AC3-Stream for sound makes me think that there might simply be a VERY slow sound driver.
With MP3s, the CPU-Load is somewhere around 50% with the Windows Media Player, and at about 25% with VLC (but just garbage). PowerDVD uses about 25%, too, but plays things correctly.
The problem with the Media Player from Windows is that it finally uses PowerDVD's routines for decoding (there is no built-in MPEG2-Decoder) and is not that optimized.
Still, I do not understand why VLC is so slow.
I have asked somebody on #voodooalert (QuakeNet), and he now tries to compile a GLIDE-plugin for VLC (which was originally written for Linux) for Windows. Knoppix doesn't include VLC, so I could not check whether it works, and I did not find the time (not yet) to install Linux (and then, I would not have any sound drivers).
So, I'm still trying to find the problem, though it might really be sound-related. Oh, and I have enough memory - 256 MB :-)
For now, I can just thank all of you, I didn't expect that many people to reply ;-)

In case you need a new sound card and have ISA slot, may I humbly recommend the best sound card of all times: Creative Sound Blaster AWE32 GOLD (eventually AWE64) - That's a true hardware card and with it, CPU usage may fall to 5% tops, maybe even less. The quality of the audio stereo output is the best I've ever heard (and I've heard a lot - Audigy's, Live!, Soundstorm...)

You can get the card for a few bucks on ebay  :)

That's the one I might choose, it's somewhere in this far too big, though too small house in an old machine. With a full WaveTable-Memory :D
I also have some PCI and even an AGP-Slot in this machine, but no newer Soundcard, but the AWE (32? 64? can't remember which one it was) should be ok. Will try in the next days.

I have had some interesting computer rigs that played mpeg2 files fine, such as my ibm thinkpad laptop with a pentium2 333mhz with a nice integrated 4mb graphics card and sound.  I found a free mpeg/mpeg2/vcd player online for this laptop and the files play perfectly. Ill post the link when I can find it again.

Sorry it took me so long, but finally I made it: I used a SoundBlaster AWE 32 with the normal Windows-Drivers, and though CPU-Load is at 100% in PowerDVD, it seems to run smooth. At least, the Audio-Crackling has gone that was there before. In VLC, it's still not working (far too slow), but the sound works now.
However, it's very interesting that I can only hear audio through PowerDVD if I put the volume to exactly 100% - otherwise, there's absolute silence.
Still, I'm not sure whether it's running completely fluently, because I have not found any FPS-Option in PowerDVD yet - at least, it should work now, though I can't be absolutely sure about High-Motion scenes.
And the CPU-Load for audio-only dropped to about 5-10% when listening to an MP3 - that's perfect!
The other problem is, that the AWE 32 with full wavetable is quite big - I'm currently running the machine without case, and I thought about building one, and now it would have to be nearly double as long...

@Elfuego: Thanks for the idea, it solved the problem. However, I think the Terratec-Soundcards are also quite nice - at least the surround ones ;-) But concerning stereo and ISA, SoundBlaster AWE 32/64 really is the best. (Somewhere, there should also be an AWE 64 here...).

@Combatman: Thanks, the problem might help to resolve this 100% CPU-Load - but maybe, this is also FPU-related, because the Pentium II is much more efficient.

why don´t you buy a K6 - 2 500 or better a K6-3 or a K-6 2+ ? The K6 - 3 gains much speed because of his second - level cache on die. I changed from a K6-2 400 to a K6-3 400 and the system runs much better. On my other system i use a K6-2+ 550 and it´s fast like hell in comparison to the K6-2. For the K6-2+ you need a mainboard which supports 2 volt, the K6-3 should run on almost every mainboard that suipports the K6-2.