You might try researching the custom settings to adjust the TV. Some people publish them. G620 is probably pretty good, but it would not support 3D. I am using an i-5 2500k in my computer hooked up to my TV. I just set the Video to the standard for HD to match My TV. If the resolution settings are set Higher than the video setting on your IGP, it may try to overdrive your IGP. If you had a video card it might be overheating the video card or cause interruptions.
I have one computer with integrated video that is only 720p. When I hooked it up I could not run it at FULL HD without interruptions in the video. So maybe trying to run it at a higher hrz, maybe you could be stressing the IGP causing poor video quality. So maybe turn down the settings on the TV for the computer source. Some of the newer TV's are more capable than we give them credit for.