How to keep warm arduino uno board with 12v dc supply

I have an arduino uno board with ESP8266 module and i have done all connection using breadboard.

Now when i run arduino uno with USB cable for long time then its not getting hot ! but when i supply power with 12v dc adapter in black barrele then its getting too much hot (i cant touch with my fingure).

Now when i remove the ESP8266 module power and test it again with 12v dc power supply then its not getting hot !

So what is the problem with ESP8266 module ? Is my wiring creates heat ?

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