how did you get 600 MHz with just increasing the FSB? you can get 6x multiplier when you set it to two, so at a 100 MHz FSB you can have a 600 MHz processor. you might need to increase the voltage a bit, 2.4V seems good enough.
But wit that increase in voltage you also need to cool the processor better. increased voltage increases power consumption that in turn increase the heat generated, leasding to unstable system or a system that simply doesnt boot!
girish
<font color=red>No system is fool-proof. Fools are Ingenious!</font color=red>