Much better volt Russian, 1.42v is way too high for high for 4.5ghz. My old 2500k needed 1.39v for 4.7ghz and no matter how much vcore I used it wouldn't do over 4.7ghz, so that was a poor clocker.
In terms off degrading like someone else mentioned each CPU tends to have a break in period, mine was the same.
See if you can do those p95 tests overnight, have a look at the as rock ivy/sandy guide here -http://www.overclock.net/t/1198504/complete-overclocking-guide-sandy-bridge-ivy-bridge-asrock-edition
One tip for asrock mobos, if yours has additional turbo voltage use that to hip the CPU vcore as apposed to offset or fixed mode. It enabled me to drop from 1.4v to 1.35v for my overclock.