De-lidding won't get you a higher O/C unless you were restricted by temps with plenty of voltage headroom. Perfect example is the 4770k i've got in at the moment, it hit 90deg+ at 1.25v and the only way to keep on going was to de-lid.
Even if you can't get the O/C higher you'll be able to reduce temps thus increasing life span of the chip (providing you don't run it with high voltage 24/7)
I'd strongly advise not putting vcore up to 1.5v in bios, even taking it up to 1.5v on a multimeter is a risky business and certainly not somewhere to be for running 24/7. Just have a look through HWBot tables and there aren't many (if any?) using that high a vcore unless under cold.