I recently replaced my motherboard, and when I did I completly reinstalled Windows 7.
Ever since I did the replace/reinstall, my monitor will not go to sleep. The computer goes to sleep fine; however, when the computer goes to sleep the monitor displays "NO SIGNAL INPUT CHECK VIDEO CABLE and stays in that state.
I know the monitor is capable of sleep as before I did my replacement it went to sleep fine (with Windows 7). When the monitor is asleep the power light turns yellow and when the monitor is active it is blue.
When the monitor is in this NO SIGNAL state (with the computer asleep), if I unplug the HDMI cable, it goes immediately to sleep (yellow light). When I plug the HDMI cable back in the monitor will stay in sleep mode until I wake up the computer.
The same thing happens if I turn off the monitor when it is in the NO SIGNAL state (with the computer asleep). When I turn the monitor back on the monitor goes into sleep mode and the monitor wakes up as soon as I wake up the computer.
I have looked everywhere I can think of for some type of indication of the casue but to no avail. All I can think is there is either a power management setting I am over-looking, or there is a setting in the BIOS on the new motherboard I am missing.
All drivers are all up to date and all Windows 7 updates are installed.
The motherboard is a ASUS P8Z68-V LV with an i5-2500 and 8 GB of RAM.
The monitor is a Hannspreee HF229H
I am using the onbaord HDMI port to the HDMI port on the monitor (no external graphics card installed), and the HDMI cable is (Category 2 certified)
Any thoughts or ideas how to fix this so the monitor will sleep when the computer does?
It is a driver issue, my problem was EXACTLY yours, worked fine, new MB, fresh install and no sleep. The reason is because many drivers have been "scrubbed" out of both windows update and even manufacturer sites, perhaps because they are older I dont know. My monitor is an Acer x263w, and it doesnt show up on acers site at all. Even when I put my serial number in it says its not found. A little googling and I found the driver for it, updated it from "Generic pnp monitor" in device manager, and presto! Back to sleep, and it WILL cause screen burn, it happened to me. Its still there lightly, but you cant see it unless its at a black screen.