Never put a voltage straight to anything in some kind of attempt at preempting instability. Rule no#1 of overclocking - only increase a voltage when needed. You should be doing a suite of tests when overclocking, and when instability occurs, testing will reveal which voltage/setting is responsible.

For 200 BCLK you shouldn't need more than ~1.15 vIOH set in BIOS. That is not to say set it to 1.15v, I'm just giving you a ballpark. Do some testing and establish what your system needs.