Scott wrote these
JP12 
  1-2 3-4 5-6 7-8 Vcore 
  off off off ON 2.8V 
  off off ON ON 3.2V 
  off ON off off 2.2V 
  ON off off ON 2.9V 
JP5 
  1-2 3-4 5-6 Bus Frequency 
  off off off 66MHz 
  ON off off 60MHz 
JP5 
  7-8 9-10 11-12 Multiplier 
  off off off 3.5x 
  off ON off 3.0x 
  off ON ON 5.0x 
  ON off ON 4.0x 
  ON ON off 2.5x 
  ON ON ON 4.5x 
From experiments that I ran using a Pentium-MMX 233 
  which I borrowed from another system, I also believe 
  the following additions are also true. 
JP5 
  1-2 3-4 5-6 Bus Frequency 
  off ON off 75MHz 
  ON ON off 55MHz 
  ON ON ON 83MHz 
  (I tried the other settings with a 2.0x multiplier but 
  the system wouldn't boot.) 
JP5 
  7-8 9-10 11-12 Multiplier 
  off off ON 3.5x 
  ON off off 2.0x