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Is it Possible to Power Down my Computer Monitors from my PC?

Powering down your monitors from your PC would definitely speed up your end-of-day workflow. Is it possible?

Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites.

The Question

SuperUser reader Squ36 wants to know if he can have his computer tell his monitors what to do:

I was wondering if it was possible to power on/off a display using a computer connected via HDMI. Let me explain :

I want my computer to power off my monitors (not standby mode) when I don’t use it (no keyboard/mouse input) for more than 15 minutes, and power them back when such input is received. My monitors are connected over HDMI, so I was wondering if it was possible to use the CEC functionality with a computer. If is it possible, then is there a hardware requirement ?

My point is that I often take a break from my computer, but forget to turn off the screens, and I would prefer to shut down the screens completely instead of putting them to standby mode.

How can he go about this?

The Answer

SuperUser contributor Synetech offers some insight and a solution:

I want my computer to power off my monitors (not standby mode) when I don’t use it (no keyboard/mouse input) for more than 15 minutes, and power them back when such input is received.

What you want is exactly what you are trying to avoid.

If the monitor is actually, fully off, then it can’t turn back on from a signal on the video cable. To allow it to turn on like that, there needs to be some sort of circuit in the monitor that remains on and active to watch for the signal. Monitors already have such a circuit, but turning them off turns that circuit off as well.

To use that circuit, you need to leave some electricity in the monitor, and that is exactly what standby does: it turns the display (and speakers, and everything else) off while leaving that one small circuit active.

With most modern monitors, there is essentially no difference between standby mode and fully off other than a tiny low-voltage trickle in that circuit and the LED on the front.

I have to pay for electricity, so we always avoid using electricity as much as is humanly possible, yet, I leave it in standby when I am using the computer and need to step away for a while (I turn both off when I am done for the day).

Instead of letting the monitor remain on for 15 minutes for nothing, your best best is to do what I do and simply get into the habit of either turning the monitor off whenever you get up to step away, or to manually put it into standby mode. What I do is to use the AutoHotkey script below (can be compiled to an executable that runs in the background if desired) to let me press ⊞ Win+M to sleep the monitor whenever I get up. Other options include using a shortcut or program, using a script or program to do it with a mouse-cursor hot-corner, or even just reducing the timeout from 15 minutes to five or so.

;Monitor Standby Hotkey
;⊞ Win + M puts monitor in standby
#m::
  Sleep 1000 ; Pause for 1sec to prevent un-sleeping when key released

  SendMessage, 0x112, 0xF170, 2,, Program Manager
  ; 0x112 is WM_SYSCOMMAND, 0xF170 is SC_MONITORPOWER
  ; Use  1 in place of 2 to activate the monitor's low-power mode
  ; Use -1 in place of 2 to turn the monitor on
return

One solution we can strongly recommend against is hooking up your monitors to a dedicated power strip in order to kill the power to all of them in one swoop. While this solution seemed practical and efficient in principle, we found that in application completely cutting power to the monitors (instead of using the power button) would frequently lead to the monitor settings getting wiped. Whatever time we saved with the single-switch on the power strip we lost in reconfiguring the monitors.


Have something to add to the explanation? Sound off in the the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.

Jason Fitzpatrick is warranty-voiding DIYer and all around geek. When he's not documenting mods and hacks he's doing his best to make sure a generation of college students graduate knowing they should put their pants on one leg at a time and go on to greatness, just like Bruce Dickinson. You can follow him on if you'd like.

  • Published 10/8/13

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