Thanks sampark1980 for your answers !
But I'd like to share some more facts and question.
First is the case of Intel's XTU. I use the latest version of the program, and when I click on the Settings menu in the top right corner the program stops working ( quite funny heh ), and some older version offer much more setting in the manual tunning section with my mobo ( btw it is a GB z97x gaming 5 ). So it's a strange issue for me. I don't know wheter anyone else experiences this.
Secondly I still have some issues with the settings given us by ken-intel. I did the changes in the Bios, then I ran XTU stress test with turbo boost enabled ( I didn't try with disabled option ), and I noticed that the cpu utilization fluctuates between 98-100 percent. And my system was also unstable dispite that I raised the cpu vcore voltage to 1.15 V ( maybe it wolud be stable without turbo boost, I dont know ), so I changed the Vcore setting back to auto. And now I don't have stability problems. For the 4,6 GHz I needed to raise the turbo boost power max because of the power limit throttling, and the cpu utilization is a straight 100% ( on all turbo frequencies, the fluctuation disappeared ).
About the RMA. I bought my cpu in late September, and encountered the overheating a few days later ( of course while testing a game ), so the chip ran on 100 C without any warnings from the system. I used the stock cooler that time. Now my new one keeps the temperature on moderate levels, but I don't know how I could make sure, that my CPU is not faulty. Any suggestions to that?
I'm not an expert on this field, so if I said something stupid, I am sorry for that.
And I am really thankful for all your help!