I am experiencing the same thing, wouldn't post at all. It's not the memory, I'm using 2Gig of OCZ DDR2 PC6400 800 MHz, non-ECC, unbuffered, yet still it won't boot with the intel e8400 processor. What a let-down. Perhaps someone from Asus can help, anyone out there? I doubt seriously if the original e8400 heatsink had anything to do with it.
Setup: Antec Sonata II case, Thermaltake 500w PSU, RAM: 2 GB OCZ DDR2 PC6400 800 Mhz, CPU: Intel 8400, Heatsink: Zalman (not the original heatsink).