Change multiplier to 45 (as you say) and set a fixed Vcore to say 1.3v and see how it goes. Should run hopefully at 4.5 ... if not increase slightly till stable. Or more likely if it runs OK at 1.3v ... try reducing the Vcore until it fails while testing, then increase it slightly until it's fine. Just don't leave the Vcore on adaptive/dynamic, as you will probably find it pulls some serious voltage under heavy testing!!!
Lots more to fiddle with if you want to. Have a GOOGLE for skylake overclocking guide, there should be a few about now.
Have fun