if your fsb goes back, how did you get it 30 mhz higher? I'd go MUCH higher (even though the 1.7 is kinda a pos - a friend of mine has one and we got his to like 2.1) just push it 5 mhz at a time until problems arise. My mobo resets itself when you OC too high but yours probably doesn't, so you'd probably have to reset it with the battery and jumper every time you go too high.
It's a lot of work but worth it - but it gets addicting.. *needs a new psu so he can chill at 3.4 ghz reliably*
Look here for some basic info on overclocking