graphic shit

Since i play, i notice textures like that in the photo but when i reduce it(game to the desk , it became as it was before just after replaying, give me any solution please if it happened to you before

http://sphotos-c.ak.fbcdn.net/hphotos-ak-snc6/282287_181213448680603_541791123_n.jpg

450 Gts 2Go DDR3 nvidia//
i3 530 2.93 Ghz
Corssair vengence 4Go DDR3 1600 Mhz
Msi carte mere p31 avec un fpb de 2000 Mhz