Asrock G41M OCing E6550

[pamarakos]

Hi all!!
I've got this package previous week as a free-gift let's say!!
I'm trying to OC my E6550 through OcTuner as I did with my previous E2140 but as soon as I reach 343 FSB freq I'm getting frozen!!
Also I'm not able to add to the multiplier which is locked at 7!!
My ram is ddr3-1333!
Can somebody with the same setup or similar one help?? I've already tried overvoltage to give little more juice to the cpu bit with no success!!What is the ideal voltage for this cpu when overclocked let's say to 3.0 ghz??
Also I've read in bios saying that if a 1333fsb cpu is adopted, I have to change a set of jumpers, should I do it??
I've read about people having success up to 3.3+ ghz

P.S. I've read some guides but hasn't anything similar with my system, should I touch ram settings in bios and also I cannot touch the multiplier even in bios (something tha I used to play with with the E2130 to hit my target)

Thank you all

EDIT1: I've tried with different settings through bios for the ram with 1N,2N, Auto no difference or even seti it manually at 500mhz or 667 or auto, same results!! One more thing is that I can't touch Vcore voltage which is set at 1.360!

EDIT2: Even if I lower the multiplier at 6 from 7 and try to go fsb higher than 342 I get frozen if it helps you propose something!!