The Problem is solved.
I tried to change the resolution a few days later. At some reason the FullHD resolution appears.
How is the clarity of text.....though video is FullHD text reqsolution is bad for me. I have DH55TC board connected to Sharp Aous FullHD through HDMI cable. As I said, the text resolution is very poor, blurry text. Are you connected using HDMI or DVI? Did you find any diff between these two cables? Have you faced such issue?