Thanks for joining the community.
I understand the processor speed is running at 3.8 GHz even if you set lower settings the speed is not defaulting at 3.4 GHz.
This type of issue might be related to your computer BIOS or the processor itself.
Please try updating your computer BIOS and also try testing the processor by running processor diagnostic tool, this will let you know if there is something wrong with your processor.
Processor Diagnostic Tool:
To add to your understanding, the speed is not defaulting to 3.4 GHz only when I set it to 3.4 GHz. Set it to either 3.3 or 3.5 it will go accordingly.
I updated the BIOS to the latest one. Still no change, though the new BIOS, F18i, is beta and my previous BIOS was the latest official which is F16.
I tried running the processor diagnostic tool and it passed. I tried without the discrete graphic card as mentioned and it's not the solution.