The issue that you are experiencing is not usual. It might be a processor issue.
I suggest you the following:
-Update BIOS to the latest version 0350. Use the Recovery method; download the .BIO file.
-After BIOS update, reset BIOS settings with F9.
-Then, run our Intel® Processor Diagnostic Tool, the stress tool will give us a better idea if processor is faulty.
thanks for response. I did both bios updating and IPDT check.
The processor fail the IPDT check on base clock step.
I had asked a SWR (replacement). And I got the replacement last Friday (Aug 26).
I just install the memory and SSD with OS installed previously.
The issues disappeared with new NUC.
Thank you for your feedback.