The Blend test will do the same, but it will also properly stress the CPU as well which results in finding out whether or not it's actually stable. I'm just relaying what has been relayed to me during my time on OCN (that's all I can do).
I mean, as far as making sure your temps are ok, Prime95's Blend test for Sandy Bridge and Ivy Bridge does this very well because nothing can get the temps up that high - especially not gaming.
Anyway, I forgot to mention something: disable "CPU C3 Report" and "CPU C6 Report" for using an Offset because otherwise the result can be BSODs and lock-ups while the system is either idling or under a very light load.
Other than that, it sounds like you may need to increase the Offset in order to increase the core voltage.
Just a side note, Internal PLL Overvoltage can be disabled. Having this enabled is usually only required if Windows won't boot no matter what adjustments are made to an overclock. Plus, disabling it enables the POST time to be about 3-4 seconds faster.