my 1.57v is too high...i got a cpu init failure this morning for the 1st time (oh no)
so have dropped back to 1.5 vcore. i agree with deeds especially with the droop factor...do you know you are getting 1.5v real?
i am sure i'm on the limit of my cpu...it "seems" to me that because i'm near my cpu limit the ram timings need to be looser and/or ram at lower speed....that's how it seems at my end anyway......btw my load temps at 1.5v are now 65c maximum.
(coretemp) lapping cpu will help if you do it properly and get a perfectly flat cpu ihs; as5 compound will help; a good tight mounting pressure of cpu sink to cpu ihs will help.