you could also just do a registry hack.......
Click Run, type "regeidt"
Expand "HKEY_LOCAL_MACHINE"
Expand "System"
Expand "CurrentControlSet"
Expand "Services"
Expand "Class"
Expand "Display"
now you need to find your Voodoo card, there may be a few 000x's thoses are all the grafix cards you have had installed at one time or another, find the one thats your Voodoo card, you can tell by its driver "InfPath = Voodooo3.inf"
Then you need to expand that folder.
Expand "Default"
Click on "Default"
Right Click on Screen in the area under "vdd"
Select "New" then "String Value"
Type "GrxClock"
for the Value put whatever speed you wisht to clock it at
ie, 190 will do 190mhz
I recommend increasing in 5mhz increments and then when you see errors, -1 untill stable.