I had the same board, with the same memory, with the same problem---When i contacted Asus, they told me that it was a documented issue and if i wanted to run with 4 sticks of RAM, i should have bought from the approved memory list. Since i did not, the only solution they could offer me was to set the memory manually (every setting) in the BIOS. To do this, stick in 1 or 2 sticks of ram and boot, then set the memorry (dont forget the voltage). Power off, add the addt ional ram and ty your luck.
I personally got frustrated (no combinations of settings would work), so i sold the boardto someone else.