I think these high vdroops are becoming larger with each step because the electrical circuit gets less capacity to deliver the set voltage. Maybe you could try a v-mod?!?
Maybe you should try to post with only one stick of memory if you didn't try yet.
I'm totally clueless at this point as well. I would expect that lower bclk would put less stress on every component connected to it and therefore providing more stability.
Did you already do a google search for extreme OC results on a R2E, performed with nearly the same cooling solution as you are using?
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