I got my broken motherboard back today. Asus mailed it back. They don't appear to have done anything with it. It came with a printout attached to it, with various form fields such as "Missing Part:", "Replaced Parts:", "Error Location:", etc. All are blank.

It appears that I could have saved a lot of time by simply mailing this motherboard to myself. Thanks, Asus.

Update: I called Asus. Turns out it's not my motherboard: it's a used one. That's right: I bought a brand new motherboard that was DOA (Dying on Arrival, return a few weeks later), I sent it back to them and they replaced it with a used motherboard. The woman that I talked with had such a thick Korean accent that I was entirely unable to understand what she was saying. I'll have to call back later and hope that I can somebody else, so that I can ask them what the hell they're trying to pull.