PII x4 925 limitations

I have a Phenom II x4 925 and a msi 880G-e41 mobo. Basically no matter how much voltage increase I cannot get a higher clock than 3402. I've also increased ram voltage and I'm not sure about cpu NB voltage but I lower the NB to 2000 or near it to keep it and HT at a solid or close 2000. Is it just a limit because how how low the core clock is? Or maybe thats just as high as it can go, like its a lower clock as a failed higher clock?

some chips are better at overclocking than others, luck of the draw.....