it's too hot arduion regulator with ramps 1.4

hi.
first, i'm sorry about my English because i'm not use English for first language.

i write this topic because I have problem with my arduino mega with ramps 1.4

when i connect the arduino just with USB Connector, it's fine.
but when i connect with ramps 1.4, arduino regulator is too hot in few seconds with any parts(motor, motor driver.. nothing)

it's too confused because i saw a lot of topics with heating problem. but they said that problem is cause by overflow.

but i didn't connect nothing except ramps 1.4. can not understand it can cause this problem.

please reply cause or solution with this problem.

thanks for reading my confused written.