Well the VIA 400 only supports 333FSB but I think the 400A supports 400FSB. Maby if you go with the 400A, 600 or Nforce2 (2nd revision) then you should get 2300Mhz+ easy. Also check the 12v rail on your PSU. Did you wire trick it to unlock it?? as a locked CPU will not let you raise the FSB as high as a unlocked CPU will.
And last check your ram run www.memtest86.com on it, but only 1 strip in at a time.