Have you tried:
Try to find your CPU's max stable FSB first, remember what your minimum NB and CPU voltages you had to achieve them stably. (Unlink your RAM, lower your HT muliplier and lower your CPU multiplier).
Once you've found the max stable FSB your CPU can take, you know theoretically what you can achieve on the standard 15x CPU multiplier. You may even find you can overclock more on a lower multiplier, as I did
.
From here you can slowly work on getting the RAM at DDR 400/DDR2 800 or more. Then you might even be able to set the HT multiplier to it's default multiplier.
Remember that basically :
vcore; affects the speed the CPU's FSB can run at.
NB voltages; affects the Mobo's ability to run higher FSB's and helps stabilize the RAM to the FSB.
HT voltage; allows to a limit, the speed the HT can maintain stability.
RAM voltage; allows the RAM to run at higher speeds with STD timings
or STD speed with tighter timings
If you have carried out your overclock in the method above and still can't get higher, then i'd say you have dodgey RAM or a poor CPU
. Also the max temps for the CPU are
55-63.