It's definitaly the W5100 chip that becomes extremely hot and uses a lot of power (I will try to measure this tonight, but I think around 4 W)
This chip consumes around 150mA @ 3.3 V
so 0.5W is usual. Chip is 'warm', but you can keep finger on it ! (chip is less than 50°C in 22°C ambient air on my desk)
> You probably have some hardware problem.Once finded your'll have less than 1W. Why is your regulator 5V ? 3.3V is needed (chip is 5V I/O tolerant when 3.3 V powered)
Is it realy necessary to stop the power to this chip, can't I just disable the chip via CS/SS pin (bring pin 10 HIGH) ?
Going further needs disconnecting power (+ spi lines to avoid drivin pins on an unpowered chip)
Toggling CS has no big effect. This chip as no sleep mode. (W5200 will have)