So far through my googling I haven’t come up with much except for moving the resistors around. Apparently according to a cached website there are 2 crystals for the o2 the reference Crystal and the oscillator. Because the cpu board has a pll phase locked loop, the reference can only be changed a smidge 14-16. I think I found the pll’s data sheet the 9135f is actually the 9135-12 but finding a compatible pll may be impossible lol. Anyway the oscillator is 60mhz so I’m thinking of buying a 70mhz to see what that does first and then hopefully do 80mhz I Doubt you could go much higher. But who knows I’ve gone on some sites where they overclocked sgis by ALOT like 50-175mhz lol cache changes as well