Why can I only capture at these strange fps rates???

[shred]

This is a spin-of of another topic I originated...
"Need Help capturing at 640x480 w/ ATI All-in-Wonder"

PIII 800mhz
500 MB RAM
7200 RPM 13GB HD (DMA Enabled)
XP Home SP1
ATI All-in-Wonder Radeon 7500
Sound=Sonic Impact S90 (Aureal)

What would cause my system to allow me to capture at 33.66 but not 29.97? I drop frames like crazy at 29.97, but 33.66 seems relatively stable. The only problem is that the audio gets way out of sync.

This is using VirtualDub in "Compatibility" mode at 33.66. When I set it to capture at 29.97, the "Average Frame Rate" still hovers around 33.66. If I set the rate to 15 it hovers around 20.1.

I get the same results WITH or WITHOUT capturing audio, so I doubt it's my sound card. I do have a VIA chipset motherboard, but I have installed the latest drivers.

Thanks in advance for any help.

[shred]

PROBLEM SOLVED!!!!!!!!!

I applied the VIA PCI Latency Patch from
http://www.georgebreese.com/net/software/
and it fixed it!

f.y.i.
I have a Tyan Trinity 400 (S1854) which has the VIA Apollo Pro 133A chipset.

Mine was one of the chipsets listed on the above mentioned site that would benefit from the patch. I loaded it and boom! 640x480 at 29.97.

Just to be sure, I uninstalled the patch, rebooted, and sure enough the problem was back. The board would only capture at 33.66 even if set at 29.97. Reinstalled the patch and everything works.