asus p5n-t deluxe

I only have a few suggestions to try

1) have you tried booting outside your PC case?

2) could you try booting with one ram stick, both in at different times just to be sure one ram module isn't faulty.

3) Remove all ram and attempt a boot, if you hear nothing, then the PC isn't even attempting to boot.

If this doesn't work, I'll try others.