BenQ MP610 user manual recommend you use the High Altitude Mode when your environment is

	A mode for operation in areas like high altitude or high temperature. We
	recommend you use the High Altitude Mode when your environment is
	higher than 3000 feet above sea level, or is hotter than 40°C, or whenever
	the projector will be used for extended periods of time (>10 hours)
	without shutdown.
	To activate the High Altitude Mode, select On by pressing Left 3/ Right
	4on the projector or remote control. A confirmation message displays.
	Press Auto.
			We recommend you use the High Altitude Mode by selecting On
		when your environment is higher than 3000 feet, or is hotter than 40°C.
			Do you want to turn on High Altitude Mode?
			Yes	No 5
High Altitude
	Next time you turn on the projector, it will show a message pictured below
Mode (off)	as a reminder during the start-up.
			Current Status
			High Altitude Mode On
		This mode is used for protecting projector from extreme environment and may cause high
			fan speed.
	Operation under "High Altitude Mode" may cause a higher decibel
	operating noise level because of increased fan speed necessary to improve
	overall system cooling and performance.
	If you use this projector under other extreme conditions excluding the
	above, it may display auto shut-down symptoms, which is designed to
	protect your projector from over-heating. In cases like this, you should
	switch to High Altitude mode to solve these symptoms. However, this is
	not to state that this projector can operate under any and all harsh or
	extreme conditions.
	This function allows the projector to turn off automatically if no input
Auto Off (off)	signal is detected after a set period of time. Press Left 3/ Right 4on the
	projector or remote control to set the duration before the projector is
	turned off. Selecting Off disables this function.
	Use this mode to reduce system noise and reduce power consumption by
Economic	20%. If this mode is activated, the light output will be reduced and result
	in darker projected images.
Mode (off)			Setting the projector in Economic mode extends the lamp timer
			automatic shutdown feature. For more information on how the total
			lamp hour is calculated, see "Calculation of lamp hour" on page 37.

34 Operation