maybe try a little overclocking, turbo core is from my opinion a waste of time just turn it off
i have mine at 4.2ghz (multiplier at 21)and runs very smooth on stock voltage, with a ZALMAN CNPSX10 performa.
something odd is that from 4.2 to 4.6ghz on 1.425v doesnt seem to gain nothing at all, so i left it at stock voltage and 4.2ghz