Thanks for pointing out everything....
Problem solved, the culprit was the TV's Source Naming System....and there was no documtation in the manual nor in the website,
It must be assigned HDMI 1(which is dedicated for pc) = PC which earlier assigned as HDMI 1 = DVI PC.
For Samsung TV there is no sound will be out from the TV Spkr if Source name is selected DVI PC, DVI Devices.
Thats it....