My monitor sometimes after long time turns off ,even with "never" turns off display

[asia23fab]

Hello all. I have a little problem. When I'm inactive, the monitor sometimes after long time period, automatically goes to sleep mode & I have to press a key or move my mouse for my screen to come back. Its not always but it happens.
My power settings are set "never" turn off display and never put the computer to sleep.Also not any screensavers.
My monitor is Benq 1920x1080 60 HZ , graphic card is Asus Strix 980 Ti.
Any ideas why it happens sometimes? Its not regularly, one time it not goes to sleep mode which is ok, but second time it will goes to sleep mode.
Any ideas? Also i checked monitor options and AUTO POWER OFF is OFF.
I am using Windows 7 X64 SP1.

Any ideas on what else could be turning off the monitor after some indeterminate amount of time and not always?

 

[asia23fab]

I said:"my power settings are set "never" turn off display and never put the computer to sleep." Even that my monitor going to sleep mode after long time of no activity. Any ideas? why

 

[asia23fab]

Sometimes, if I turn the monitor off, and leave the computer on

overnight, when I turn monitor on in the next morning it won't display anything because monitor automatically goes on sleep

mode. I have to press a key or move my mouse for my screen to come back.
I have every sleep and auto-powerdown function turned off on my PC, I use no power saving mode whatsoever.
Sleep mode, hibernate,turn off display are set to never.Also i am not using any screensavers.
Any suggestions why its going itself to sleep mode?

AUTO POWER OFF function in monitor is OFF.

Monitor is BENQ G2250.