You shouldn't need that much voltage. As you get higher, it's actually possible for it to start hurting you faster than it helps.

I suspect your problem is Turbo and Cool'n'Quiet being enabled. Your Turbo multiplier is going to be +2x, and if it is still enabling at times your CPU will be trying to run as high as 4200 MHz and likely at a reduced voltage of 1.475V. You might try editing your P-tables using K10Stat to make sure this isn't happening.