Anyway to actually limit fps?

I've tried both Glide and D3D(Voodoo3/3k) and have the vSync and all the effects enabled but still on some maps my fps is going through the roof. IMO when the fps starts going past 90+ its just as bad as it being too low. Not sure what the exact effect is I'm seeing(screen tearing?) but it's enough to about make me nauseous after awhile. Are there any 3dfx features I need to disable/enable? Any help would be appreciated.

hmmm

Actually I don't have that impressive of a system.
AMD K6-2 400 oc'd @451MHz(high as it will go and stay stable)
128 RAM
Voodoo3/3k AGP, 1.05.00 drivers
Win98
16" monitor @1024 16bit color

I've tweaked everything possible and the only thing running when I game is my firewall software. And the same thing happens in U1 and UT. Now there are maps the system just can't handle and times when I do lag but I want to find a way to cap the refresh rate during those low poly/load times like when your scanning a large open area. At first I thought it was lag but then I started watching the fps and found out it was when the fps was going over 90+ it started looking bad.