System unit turns on but no display

Hello,

it's been a week since I turned my computer on due to not portable.

I turn my system unit, the monitor doesnt display anything, it says NO SIGNAL.

i can't turn it off when pressing the power button.

restarts seems not responding

dvd lights on, but can't open it

no lights on keyboard

cpu and video card fan is running.


i tried the following and nothing hapened:
remove and return the power cords inside the System unit
remove and return the cmos battery
switch the ram to other slot.
clean the ram using eraser
remove the keyboard, mouse, hdmi cords