gingerbee you're correct that Athlon 7750s are based on Phenom 1 cores.
I don't own the dual core 7750 but I use a Phenom 9950 in my main rig.
It looks like you're running a southbridge that doesn't support ACC. (e.g. not the SB750), which is needed to get that one last "bump" of clock multiplier out of most Phenom 1 based CPUs. For my Phenom 9950, I can't get it over 3.0 GHz without setting ACC to +2 for all cores. If you don't have ACC, you may not be able to push it much higher without doing something insane. Did you try tweaking your "CPU-NB" (called NB VID in AMD Overdrive)? (this is different from northbridge voltage) I increased it to ~1.35V to get another multi out of my CPU as well. Also if you have a "CPU Tweak" setting, you can disable that to drop your temps a little, and hopefully achieve higher clocks.
I'm currently running at default clocks and undervolted though, as I no longer need my rig to warm my room