For everyone helping, here's what the mobo looks like:
http://www.digital-daily.com/motherboard/asus-a7n8x/
and here's the manual:
http://dlsvr03.asus.com/pub/ASUS/mb/...1859_a7n8x.pdf
Seriously, take the entire motherboard out of the case, put it on a wooden table, piece of 1/4" plywood, or even the mobo box itself and bench test it. I used to do that all the time when I ran into issues like what you're having. That is the best true test because you eliminate accidental grounds. It may still be the processor but like I said, 9 times out of 10 it will beep when the processor is toast since the mobo can still go through it's self check and then gives you an error beep (it will do the same thing if the RAM is bad). I would also double and triple check that all your jumpers are set correctly according to what you've got set up.
Here's some examples of what I'm talking about:
All you want to have running is the PS, Mobo, Processor, RAM, video card. Once you have that running and can get to the BIOS, then add more stuff (HD, CDROM, etc) until it the entire system benches fine. Once you have that totally running, then install it all in the case and you should be good. Also be sure with the case that all the mounting points all go to screw holes. I've seen cases where Mobo's have different configs and some may have screw holes where others do not and vice versa. If there is a mount with no screw hole, it will ground right into the back of the board and short out the voltage and usually prevent any hope of posting until it is fixed. If you can't even get it to post on the bench and the RAM tested fine, then I'd try getting a new processor. If the mobo won't post with good RAM and a new processor, then exchange that mobo for another one.
When you try and post are there any red/green LEDs lit up on the mobo?