The Paladin said:
haswell cpu vcore should never exceed 1.3 v or you get problems.... at 1.088 your doing ok, but I would set it to 1.29v and see how much more you can get out of it your z97 board should handle it just fine. and you should be able to get 4.5 from it.
Ran mine at 1.4v for 2 years without any issues. Only after my 5GHz adventures at 1.5v could it no longer hold 4.8GHz stable, though that could have also been my cheapo motherboards vrms frying.