You'll want to start with your target baseclock and stress test it to find the lowest QPI voltage that still passes the tests while you keep the RAM and CPU on low multipliers. You then overclock your RAM and find the lowest voltage (or use the rated values, just make sure the QPI and RAM voltages are within half a volt of one another). After all that is stable, you set the CPU multiplier to match what you were looking for and then find the lowest stable voltage. After that's done, you can turn the power saving settings back on in order to lower your CPU multiplier, voltage, and temp while it isn't under load.
If it just won't run stable at higher clocks even with a lot of juice (1.35+ volts), then that probably means your CPU was running on very high voltages up until now and will have to stay at lower clocks is all.