Monitor won't wake up when coming back from sleep (Windows 7)

I played a bit more with Windows 7 Power Options to find a workaround. That's what transpired (your mileage may vary):

• if you change Turn Off Display to "Never", but leavePut Computer to Sleep set to say 30 min, your display should be turned Off or put to Sleep automatically by its hardware once the PC will drop its video signal at going to Sleep. At PC Wakeup the monitor will get normally recognized, and the picture shows up on screen. If you need to switch display Off earlier than that, use Screen Saver instead of Turn Off Display option.
• if you also switch Off Hybric Sleep option, your monitor wakes up to a full resolution screen very fast, as the PC doesn't need to initialize and access hard drives first, as the pic is read from RAM. You generally don't need Hybrid Sleep option On, when hooking the PC to power via UPS, since there should be no power interruptions. If you leave Hybrid Sleep On, Win 7 will read saved data from HD instead of RAM - seemingly a bug in case there was no power shutdown. So if you have several HDs in your system, they will need longer time to all spin up again, and the monitor on PC Wakeup will show the lowest VGA resolution pic - not sure where it gets this alternative data from, possibly from RAM. However, if you then typeCtrl+Alt+Del and then Esc, the low resolution pic will be replaced by the same pic of normal resolution.

Hence, if you experience no Monitor Wakeup, try using this workaround in Win7 Power Options:

• change Turn Off Display to "Never"
• switch Off Hybric Sleep

- Enjoy...

If you still experience the same problem, try switching On in BIOS the option "OS Controls Plug-n-Play Devices". In my case it delivered more consistent results at Monitor wakeup.

I have the same problem: the monitor doesn't wake up after going to Standby for significant period of time (several hours or overnight), regardless of being sent to standby manually or automatically, with or without sending the PC to standby. It only occurs in Win 7 64-bit, despite the PC is hooked to power via UPS, and data is even saved to disk at Hybrid Sleep selected. I have a multiboot OS install on the PC, and the problem is non-existent in Win XP 32-bit.

From what's reported above, all symptoms are possibly caused by different Win 7 deficiencies and incompatibility with various video drivers and monitors. I'd say what is common to all of the symptoms: the monitor fails to re-initialize when the system resumes from Sleep. Win 7 doesn't seem to prompt on wakeup a video card driver to query the attached monitor's EDID chip to ID the monitor, while its previously identified ID is lost or can't be retrieved after lengthy Standby (why is that?). As a result, the system sees no monitor attached, even if one turns OFF power to the monitor, and then turns it ON, it still won't be seen by Win 7. In other words, Win 7 capabilities to query the attached monitors get partially lost at wakeup - possibly because it relies on monitor data in RAM, but can't access it. Partially - because at times it IDs only one monitor out of 2 attached, and it may ID at wakeup some monitor models while failing others.

Only when the PC is rebooted, or sent to another short term Sleep - Wakeup cycle by its Power Button, or Ctrl+Alt+Del is pressed (not always helpful, but may work), or an HDMI cable is removed and then re-inserted again, Win 7 prompts the video driver to query the monitor's EDID data again, ID its type, re-initialize the monitor and retrieve video memory from RAM, thus showing on screen last picture saved before Standby (except after reboot).

I don't know why MS is so slow to fix this very long standing issue, probably due to large varieties of possible hardware model & controller combos. I did notice, at times the issue can be fixed by a new or older video driver reinstall, but at some point down the road a new Windows Update (often seemingly unrelated) bricks the monitor wakeup feature again.

I just thought I would add to this thread not because I have a solution but another symptom.

I have been suffering with exactly the same problem as they guys above and it seems to have started in the last 4 days or so.  I have tried changing the monitor and it resulted in the same problem, I had some success with re-seating the RAM but then after a day or so the problem came back again.

I figured I would bite the bullet and see if a re-install of windows would help but this resulted in the problem occuring during the windows install!  Im now partially re-installed but no way of getting the monitor back on.

Really hope we get a resolution to this.

The simplest and safest fix is to shut the monitor off.