I think you guys might be going in the wrong direction on this one. A common mistake is assuming that because there's no video, it must be the graphics card. This generally isn't the case. If you've already reseated the graphics card plenty of times then for now we can rule it out.
Generally when your computer powers up but there are no beeps it's the CPU or motherboard.
Make sure you have only the following hooked to the mobo:
Keyboard, power, RAM, Vid card and absolutely nothing else.
Try powering on..if it doesn't work lets try troubleshooting hardware.
Remove the Video card and boot up the machine. If same problem occurs it's not the video card. However, if the machine beeps while the video card is out, then you can pretty much bet that the card IS the problem.
If it doesn't do anything still, put the vid card back in.
Now remove the RAM. Same thing applies, if you get beeps, the computer is telling you that the RAM is missing which suggests the RAM was either improperly installed or is a bad stick.
Of course the easiest way to test the RAM and the Vid card are to throw it in another system if you got it.
Now if you've tried powering on with no RAM in and you still get no beeps....chances are it's the CPU or the motherboard at this point.
The only way to test the CPU is if you can throw it in another machine. Other than that you gotta just kind of be in the dark as to whether it's CPU or mobo in this case because there's no real way to troubleshoot those unless you can throw it in a known working system