i have seen the msi p67gd65 going up to 4.2 @ 1.4v with ocgene (auto overclock) and that within save range so i think you stil have a lot of room
but i whont go over 1.3 for now yust 2 be save and go up max when the limits are known
i think no 1 can realy know the max vcore yet they are 2 new
my 2600k and GB ud7 wil arrive very soon ill try 5ghz and see if its save or not
btw nice oc ( 4.5ghz @ 1.22v ) what are your temps?