Your rig getting unstable above 2.9?At what is your HT running at that speed?You can raise the FSB on your MB but then you'd also have to lower your HT multiplier to keep it at around 1000Mhz. My 4000+ is running at 2.8 Ghz with 2-3-2-6 1T timings on my Corsair CMX1024-3500LLPRO's.
It would probably be under the same menu where you adjusted the AI clock I think, have to choose the "manual" option somewhere.What mobo do you have?The manual will probably help you out if you're unsure where to get the options.
I thought the FX55s Multiplier was also unlocked as the other FXs are, simply set the CMOS settings to manual instead of the AI, and increase the multiplier,,, 2.6 is a 13X multi, 2.8 is a 14X, 3.0 si a 15X, Etc.
You'll have to increase the V-Core to run higher multipliers, but everything else stays in spec, make sure you have good cooling!!!
Watch the V-Core carefully as ASUS M/Bs run those voltages higher from the git go, you should be able to hit a 15X multiplier around 1.4v, but use that information to sneak up to where you want to go, don't try to go straight there.
You probably won't get past 3.0GHZ on air, you have to keep it cool, thats the most important thing!!!
I had my FX57 @ 3200MHZ on water but when I went back to air couldn't stably run a 16X multi on air, my FX60 is essentially 2 FX55s, and on air I have them running a 15X Multi @ 3.0GHZ using 1.4V V-Core.