tried that for regular testing..
vtt : 1.24v
vcore : 1.48v
vdimm : 1.84v

no problem at about 10hours run..

here what i see from intels datasheet,with a %10 range, i guess pushing vtt to 1.5v and vdimm to 2.1v will not be problem [DO NOT TRY because i said]