No monitor display, please help

[jellydoughnut217]

So last night my computer was working just fine, i turned it off and went to sleep. The next day i come home from school and turn on my computer the fans start up, the lighs go on and everything seems fine, except my monitor displays nothing. It just displays a message as if i just had my monitor plugged into a power source, but not into my computer. I also do not hear thje startup beep. It's not because my monitor is bad either, because i tried a different monitor on it and it still didn't work. I've tried reseating the video card, taking out my RAM, using only 1 RAM stick at a time, i've hecked all my connections and even unplugged everything except my gpu cpu and 1 stick of RAM. THe computer is only a year old, this shouldn;t be happening.

specs:
Motherboard:Asus A8N-SLI
CPU: AMD athlon 64 X2 4400+
GPU:7800GT
RAM 1 gigabyte pc3200