New computer nothing on screen when power on

Hey ive just fineshed putting my new computer together
motherboard :ASUS P6T SE
processor :Intel Core i7 920, Box, LGA1366
Hdd :Seagate Barracuda7200.12 500GB HDD SATA
grafickart :ASUS EAH4890/HTDI/1GD5
psu :Corsair CMPSU-1000HXEU, 1000Watt
ram :Corsair Twin3X XMS3 3x2048MB DDR

iv put everything in place like i do when i make a new pc. i plugin the screen and press power and nothing happens on the screeen the fans gpu cpu starts the hdd starts. ive checked all the cabels and the ram diffrent ram block in diffrent slot ive tryed using another graficscard andthesame things happen do you have an idear about waht to do ? also tehre is no beeping sound error code

im having a freind comming over later today hes more neard then i am and we will try to fix it i willreturn with an answer when i know what to do there are other people with this problem but no selotiun in their threds