Could you check/log the temperatures while you're playing games?
This message was posted on behalf of Intel Corporation
I recommend you to verify the memory speed in the BIOS; they should run at 2133MHz at 1.2V or 1.25V. The games are demanding a lot of resources of your system.
By default, NUC fan control is set as “Balanced” I suggest you to change the setting to “Cool”. Get into the BIOS>Advanced>Cooling tab, At CPU Fan Header window the first option says Fan Control Mode