The Apci modes are set wrong in the bios.
After 30 mins of no activity a signal will be sent to the graphics card telling it to power down, the screen will go blank.
However if the wrong Apci mode is set in the bios the signal to wake the card up is not sent or received so its why the screen is black but the system seems like it is still running.
Look in the power section of the bios, Apci and check what mode it is set to. S3,S4 ect.
S1 is a bork !
I have checked all the settings, but there is nothing coming close to ACPI or S1, S3.
Everything that comes close to power is like this:
- EPU Power saving mode is disabled
- APM: ErP disabled (everything in the APM section is disabled)