This switch is for overclock use with liquid nitrogen.
It will allow system boot up properly when CPU temperature is in very low temperature.
Normal operation or overclock does not require to use this special switch.
Here is the LN2 switch's function wrote in user manual:
:[When the LN2 mode is ON, the motherboard can boot at an extremely low temperature (-130°C).
Note: CPU will run at 800 MHz speed when apply LN2 to ON.
