Can't get 965BE C2 past 3.5GHz even with 1.5250v.

what motherboard are you using? what case? what temps? and more importantly how many sticks of ram, at what sizes and speeds?

Do you use multiplier only to overclock your processor..?

if yes, then try to combine multplier and your fsb clock..

my old x4 b50 (unlocked from x2 550) can't pass even 3400Mhz with multiplier only, even at 1.55v..
but with a good combination between multiplier and fsb (17x212), i can go to 3600Mhz with rather low voltage (1.375v)

yes. here is how you're going to do it. turn your ram speeds down as low as they'll go. turn your HT and northbridge frequency down as low as they'll go. now drop your cpu multiplier by -0.5 from stock. increase the cpu frequency the required amount to keep your cpu speed the SAME as when it's at stock. do not touch your vcore or any other power feature. We're trying to find the max FSB overclock your chip will accept. most of the C2 phenoms perfer fsb overclocking to multiplier overclocking.

example. your chips base cpu speed is 3.4ghz which is a cpu frequency of 200 x 17 cpu multiplier. knocking the multiplier down to 16.5 will mean you need a cpu frequency (fsb) speed of 206.

save and restart your computer, see if you'll load into windows. if you do, restart and lower your multiplier by another -0.5, which will require a fsb/cpu frequency of 213 (rounding up).

keep doing small drops in your multiplier by -0.5 and keep bumping up your fsb in response until the computer fails to post or load into windows. That is the max FSB overclock your cpu will live with.

now we bump your vcore by 0.0125V and see if your system will load into windows again. this is where it gets a little cloudy... see there are several voltages to play around with when FSB/cpu frequency overclocking... vcore is the main one, but so is the cpu/nb voltage... we'll keep to the vcore until several bumps in vcore don't help. then you'll walk the vcore back to where you started and start to bump the cpu/nb a little (0.0125V). probably a few small steps... it won't need much. basically we're going to bring the multiplier, step by step back up to 17.

once the multiplier is at 17 and you can load into windows, you're going to load up hwmonitor, and prime and see where your temps are at. see if you're prime stable really. this is where you're going to need to play with voltages a little more (likely). remember, small changes, try to keep only to vcore, but if it isn't working then you'll have to use the cpu/nb or just the base nb voltage.

once you're prime stable, and temps remain under control (no guarantee, if temps are out of control, or you can't stabilize without obscene voltage numbers, you'll need to bring back the fsb by -5, and try to stabilize there)... you'll need to bring your ram back up to 1333 (or close enough) and your nb and your ht back up to close to 2000. see if the system is prime stable under those numbers. if you are and you still have good temps and under control voltages you can try to bump your multiplier up by 0.5 and see what happens.

i sorta posted that long litany because you need to know how high of a FSB your cpu will work with. they are limited, not by voltage or temps but by motherboard, psu and cpu. since you don't know how all those parts will interact you need to learn what the upper limits of your fsb/cpu frequency (you'll notice i called it both, and you're right, they mean the same thing... mostly)... so you know what's possible. if you set your cpu frequency to 219 and your chip will only go to 215, no amount of voltage will ever stabilize it.

and yeah. generally speaking the c2 phenom IIs loved their fsb/cpu frequency overclocking. they also tend to hit a wall HARD with their upper limits. meaning when they get to the end of their overclocking, the temps and voltages go sky high just for a small bump in speed.

which actually is almost like how most phenom's act. my c3 (same 965) likes both fsb and multiplier, but one thing is for certain 4.0 is as fast as it will go and stabilize and it takes WAY more vcore and heat then i ever want to stick into a cpu. I even got it to load into windows at 4.2... but yeah... even idling the temps were out of this world. ended up backing it down to a nice happy 3.8ghz... almost no vcore increase, almost no heat. and plenty of speed under the hood (3.8 is where the phii x4 965be sorta tops out on the gains from overclocking)