Should i set gate a20 to Normal or Fast? - Fast should work, not too important
PCI/VGA Palette Snoop Disabled or Enabled? - definitely disabled
OS Select for DRAM > 64mb: Non-OS2 or OS2? - Non-OS2 (or are you running OS/2?)
Video Bios Shadow: Enabled or Disabled? - Enabled is slightly faster for some stuff
Video Bios Cacheable:Enabled or Disabled? - Enabled is slightly faster for some stuff
Memory Hole at 15mb Addr: 15 - 16mb or Disabled? - definitely disabled
AGP Aperture Size: 2,4,8,16 or 32mb? - shouldn't matter for Voodoo3 (no true AGP features), with a different AGP card I'd set 32MB (unless you have very little RAM)
Spread Spectrum: Disabled, 1,5%(CNTR) or 1,5%(DOWN) ? - disabled should be OK
DRAM Read Pipeline: ON/OFF? - ON is probably faster, if unstable you could try turning it off