|Has this system ever run or is this a new build?|
If it is, pull everything and bench test it.
If it has worked, pull the video card and try the on-chip graphics.
Try it with only one stick of memory.
Remove anything not required for posting, including hard drive.
Reset all connectors.
Make sure CPU fan is plugged into the CPU Fan connector (some motherboards will not post unless there is a CPU fan installed).
Clear CMOS, then if it posts, reset to defaults and then manually set the required settings.
You have to be a little bit crazy to keep you from going insane.