Well,
your problem seems to be board-independant (more or less).
The only board-oriented tip I can give you is to turn off
system Turbo -
because this will simply increase the FSB by some silly amount (1-3MHz) -
but might be enough to thwart your goals. 120MHz+3MHz not EQ 120MHz. Yeah, ok.
I don't have your CPU (2.5@100FSB), so I cannot make any empirical observations, however....
Any CPU with a internal multiplier of 25x(!) is going to be a tough OCing candidate.
With every MHz increase in FSB, your looking @ a 25MHz increase in core speed.
(Like you didn't know that, right.)
That aside, it is a general fact that incrementing the core voltage will help to stabilze an Oced cpu.
It is also a known fact that overvolting any electrical component can lead to a crispy critter.
Makes for a good paperweight, but otherwise useless.
The key here is
moderation. But you already know all this.
So I don't really understand what kind of little miracle you expect your mobo to produce
None the less, good luck!
CU,