I had a week 43 locked chip...but I raised vcore to 1.7v (1.67v actual), bumped up nb chipset to 1.6v, vdimm to 2.7v and took it straight to 200fsb...ran prime for 48 hours....
After that Istarted bumping the vcore down and eventually at 1.65v still had prime stability for 6 hours of testing....The cpu was not mine so ultimately I bumped it back up to 1.7v bios and called it good since I knew it primed for 48 hours ran every test I threw at it with SETI, POV-Ray, multitasking, TMPGenc mpeg2 encoding, gaming....Rock solid so I felt comfortable giving it to my friend and saying "have fun"....
I left it at 1.7v with no fears as the temps only loaded to 49c on that particular board...I had on of the new copper core retail HSF with improved fan and fan to hs connection...very quiet and good airflow....