Replace the motherboard(s). This has been a really common problem. Based on my own hands on experience, I would recommend another manufacturer.
Updating the bios using the utility provided will usually increase problems, not solve them.
I had the same problems, and described them to our local college professors. They immediately recognized that I had an Asus motherboard, before I even mentioned the name brand. These computer guys were well aware of the symptoms and the solution.
I was skeptical at first, but I ordered a Gigabyte board on faith and recommendation. The board started right up and ran on the first try, I did not need to reload any software, or change any hardware. I did load GB drivers and removed the Asus drivers.
Guess what? it's been running without a hitch ever since. I can spend my time USING my computer, instead of trying "experiments" to make it work. Never been happier since I dumped the Asus board.
Now, learn this lesson. You can spend unlimited time reloading software and drivers, resetting memory timing, and begging other users for "work arounds," to try to get the Asus to keep functioning.
OR you can install another board, start the computer, and enjoy.