Yea, I've been there with my 7 yr OLD system with a 478 socket mobo with no voltage control or any adjustments really for any overclocking.
That's why I use CPUFSB to
OC my system...it was the only way I could and I was limited on the
OC because I couldn't raise any voltages on anything...
Even still, getting it to run at 2.68 @ stock vcore did help performance some.
CPUFSB Podien's Shareware