Hello tanvir130:
In regard to your inquiry we just did the same thing in one of our Intel NUC's, we erased 1 of the 4, there was only 3 showing and what we did was a turn the device off and on and the fourth processor came back
Another thing to try if the step above does not work, will be to get in to device manager look for the option "action" and then select "scan for hardware changes", that should work.
Any questions, please let me know.
Alberto
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