@droftarts @Jords27 OUT2 can safely sink more than 5V, it's just that the OUT2 connector is provided with 5V to match the Roto hot end fan. However, if you use a 4-wire fan then you would connect OUT2_NEG to the PWM control input of that fan and it won't see more than about 5V anyway. You will need to invert the OUT2 pin in your M950 command.