masitti
The 1/5 divider kicks in automatically with BIOS F11, but you have to go thru a routine for it to work. The first thing to make sure is that you have the memory set to Normal(Fast and Ultra dont work). Second is to set the memory to 266, this actually means set to 2x FSB, wheras 333 means 2x (fsb+pci). Then you have to set the FSB TO 148-154(148 for me), save, exit and re enter and set to 166 or more. The only drawback is that if you shutdown you will have to go thru this process again, the only solution I have found is not to shutdown but just go into Standby. I hope this is sorted with the next BIOS Rev. I have heard that people with GF4's have probs getting the 1/5 to work but cant confirm this(only have a GF2), but as you have a GF3 you should be OK.
Hood