My Acer x263w displays "No Signal" right in the middle of the screen, unmoving too, when my Win 7 x64 PC is asleep. It is connected to an ATI 5450 chipset video card via HDMI.

As explained above improper cable connections is one of the reasons for the No Signal issue on a Monitor. Therefore, the first thing that you should do is check your cable connections. Try the ...