I'm new to this but have tried to OC already. Problem is that i can't get my X2 4400 939 past 2.5ghz stable. I'm pretty sure my ram is limiting me but just thought i'd ask anyway. Currently i've turned everything back down to stock speeds. I've tried different multipliers, ram spds, etc. I haven't tried much with vcore or dimm voltages (if i kill it my "Better Half" definately won't let me get new parts. Am hoping to upgrade soon as another year approaches with more grey hair (no, i am less than 25 thanks) to a e6300, DS3 etc. etc. Here's a list of what i'm running:
Your memory may be holding you back. You mentioned not having adjusted your vcore. Might try increasing it some. Can definitely help stability issues when OCing. Might also be limited by your mobo. I assume it's a socket 939, dont' have any experience with those. Some boards are good for OCing, some aren't.
if i were you, i would set the memory divider to 4:3 to run the ram at stock speed but the cpu oc'ed. i think on your mobo you have to set the memory speed index (or somehting like that) to 333mhz instead of 400, then set the fsb (i know its amd, no fsb, but that what its called, that or cpu clock) to 273mhz. this should make your cpu run at 273*11 (or whatever you set the multiplier to, i would recommend no higher than 8 to start) and your ram run at 200mhz (ddr400).
try that and see how high you can get the cpu that way.