When Turbo Boost is enabled, the highest your processor could go is to 3.9GHz. There are not other settings you can change since this is not an unlocked processor.
The Intel® Turbo Boost technology feature is auto-managed by the processor having a balance between the power consumption and the chip heat.
The maximum Turbo Boost speed won’t be reached by all of the processor cores at the same time, the value is assigned to the cores being used gradually at the moment the Turbo Boost kicks out so it is possible that only one core reaches the maximum Turbo Boost speed assigned by default.
Intel® has a tool that will test every single component inside the processor and then will generate a report. I recommend you running the tool named Intel® Processor Diagnostics Tool. It can be downloaded at the following link: https://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&DwnldID=19792&lang=eng&OSVersion=Windows%207%20%2864-bit%29*&DownloadType=Utilities%2C%20Tools%20and%20Examples
Thank you, Sylvia, for your reply!
Yes, I know the facts about the Turbo Boost technology. That is the reason why i am only testing with one or two threads running at the same time.
I solved the wrong set clock multipliers by myself. I did the following:
1.) Remove CMOS battery.
2.) Remove secure jumper for "reset". (dont know if this was necessary)
3.) Boot into BIOS
4.) Wondering about a set clock multiplier of 0 (0 GHz would be funny)
5.) Loading BIOS defaults
6.) Seeing the correct set clock multiplier of 39, which will result in 3,9 GHz with turbo
7.) Found a bug: I could overlclock the integrated GPU (but i didnt). Now the setting is locked again.
Still with prime95 and IntelBurnTest I dont get 3,9 GHz.