if you can.. try sticking to 100mhz/133mhz etc speeds with the appropriate divider.
Depending on your hardware the bus overclocks are not peripheral friendly. Some hard drives will get corrupted data, lose it's master boot record, windows registry can get corrupted, more chances for system locks since it's not JUST the cpu being overclocked.
With everything running within spec any instability can easily be traced to heat or insufficient voltage to the processor.
benchmark your system at max processor speed with standard bus/fsb speeds then add those tiny increments and see if the added risk is worth the speed increase. Some odd fsb speeds can actually UNDERCLOCK the agi/pci bus because of the divider etc.. I think some speeds are like 95mhz fsb or whatever is equivalent past 100/133. (124, 150 fsb?).
I think these underclocks is actually what allows some people to get those crazy high fsb's. If you're CPU/ram can handle the speed with your peripherals/bus speeds underclocked then it might be worthwhile. Not sure what the effect is on the peripherals at lower pci/agp speeds other than slightly slower data transfer across the bus. Then again you gotta ask yourself if having some components run sub spec while you squeeze every last bit out of other components is worth it.. what is the performance tradeoff and risk to the parts running over spec?
I use a measly celeron 600@900mhz.. I can boot up at 103fsb(reads at 933mhz) but the speed increase was tiny. I could probably do 112 fsb if I had better cooling/voltage but I can run it at 900mhz using default voltage/standard heatsink cooler and I'm not straining any other part of my system. The one time I did try 112fsb my registry got corrupted