Originally Posted by mystica555
i only have seen a few of them personally) seem to overscan on HD channels connected even via HDMI.. I'm not entirely sure the reasoning for this.
It is in the standard. TV standards, including HDTV, specify that a certain area of the frame should not be shown in typical trim, so that there is a bit of tolerance to play with for setup of picture size.
It was designed this way in the CRT days. CRT picture size always varied a little with temperature, age, picture brightness etc.
Furthermore in analoge transmission there could be transient effects at the picture edges that should not be visible on screen. Hence the overscan.
For LCD and plasma, with digital transmission or PC output, it is completely superfluous. But it is in the specs so most TV set manufacturers abide by it.
It causes endless problems for those that want PC output with 1:1 pixel mapping to the screen resolution, but apparently those are not the main clientele for them.