I have an nVidia GTX 295 connected to my Sony Bravia 52" LCD, through the PC input. I notice horizontal lines sometimes when I play games and videos. I tried the HDMI input and the lines disappeared, but everything isn't as clean or sharp as it is with the PC input. Any ideas why this would be happening?
I had the same problem on my Samsung 610. I had a VGA PC input but never tried it because I was told the VGA input won't display full HD resolution (limited to somewhere around 720p resolution).
So right from the get go I hooked up to my HTPC via HDMI and yeah it wasn't sharp. My solution was to go into my TV menu and label the input as PC. All TV's have a little bit of digital overscan (they chop off pixels from the top/bottom/left and right and resize) This is fine for TV but with the PC input is unacceptable. Labelling this input as PC turns off all processing and overscan.
The other thing is that my ATI card defaulted to 1% overscan also which I had to change to 0% and everything was perfect!