Something weird that seems to happen to everyone and I have no idea of what to do...
I have a laptop with Intel HD and Radeon HD 6770M running Win 7
The display started going black after a minute of inactivity, but did not go off. I have an external display hooked up to my laptop and the display did not turn off. I have set the sleep / turn off times to "never" for all power levels and plugged in / battery. I reinstalled my GPU drivers. I rebooted in safe mode, ended the explorer process and waited a minute. The display still goes black, but does not turn off.
There is a bug in Win8 that prevents it from putting monitors into sleep mode correctly. It's hit and miss though, sometimes it works sometimes it doesn't. Don't waste your time formatting or reinstalling, it doesn't fix it.
Basically what happens is, the monitor DOES turn off, for about 30 seconds-1 minute, then sometimes it will turn back on with a black screen. Other times it stays off. There isn't any pattern to it.
Good luck waiting on Microsoft to fix it though, I doubt they will even acknowledge it, they will just say "check your power settings". Maybe it'll be fixed in Win9.
by the way,he said that he is using win7,and if he had "set the sleep / turn off times to "never"then the problem may not be only of power issues,just check the power plug and RGB/DVI plug of your monitor,it can also cause weird problems sometimes.
Try it and keep us updating,we will try to help you.....