I/O input pins voltage 5V

Official Hardware Mega Due
5

Graynomad:
From the Due product page

Warning: Unlike other Arduino boards, the Arduino Due board runs at 3.3V. The maximum voltage that the I/O pins can tolerate is 3.3V. Providing higher voltages, like 5V to an I/O pin could damage the board.

Rob

Maybe it would be better that the Due-Board doesn't have an 5V Pin on it so it's clear that the SAM3X8E isn't for 5V and nobody makes a mistake and jumpered 5V to some I/O Pin.