(Graphics Or Display??) Weird problem please help

Hey everybody! Okay basically i have had this weird problem for over a year now and its back and im just stumped as to what it is. My system is cd2 e6400, asus p5n-d, 2gb pc6400 kingston, and 1 8800GTS

Alright here it goes. my first monitor i used was the viewsonic vx922.my computer would post normaly like it does. but then when the monitor went into idle it wouldn't come back... well when i would come back and try to wake it back up it wouldn't come back on. it got so bad that when i would even re-boot the computer it still wouldn't post so the computer is posting, im just not getting anything on the screen. well at the same time i was getting a 1 long, 3 short beeps which indicated it was a video card problem. well thats where the 2nd 8800GTS came in. so i plugged it in and same thing no post. It was making the single beep like normal i just couldn't see anything. So i thought maybe the monitor is just dieing, so i switched monitors and what do you know i could see picture and everything was posting normal. Well that was about a year ago.. Well the problem is back with my 2nd monitor same thing, wont wake up from being idle. and now i cant even see it when i re-restart my computer so i cant even do anything on the computer pretty much.

Now it wont even post i cant do anything expect change out the video cards.. Do you think the wire from the monitor to video card maybe could be going bad? And the psu is 28/29 volts so there's plenty of power for just that 1 card.. So i know its not the video card as both of them do it. and how can 2 monitors just both go out like that? please if anybody can help its greatly appreciated as i need my machine back.