Seems like 720p not 1080p

Hi,

I hook my ps3 with dell s2309w which support 1080p with dvi>hdmi cable. In the ps3 menu it displays 1080p but when go into games which support 1080p, it seems like 720p picture not sharp as 1080p (compare the icons and front on ps3 menu when press ps botton while in game with before come into the game).

Anybody has anwer how to set it to 1080p