No video on lcd nor external, fans spin video card?

I have a 2.8Ghz 24" iMac that does not display anything on either the LCD nor external devices.

When you press the power button you can hear the super drive, HD, and the fans spin up but no video OR chimes at all.

I have tried resetting the SMC, booting with comand+opt+P+R, I have re-seated and tried different ram sticks, and tried attaching a secondary monitor with a Mini DVI-DVI.

I have checked and re-seated all cables to the LCD and they are all secure and in place.

I am getting LED lights 1,2,3 but NOT 4.

I am thinking this is possibly a video card but as it is a customers computer we can't afford to be ordering wrong parts for this (we have no local computer stores that deal with mac or carry mac parts in our area). Really hoping someone can help me accurately narrow down the issue here! Thank you so much guys!