"4 x DIMM, Max. 32GB, DDR3 1333/1066 Hz Non-ECC, Un-buffered Memory
Dual Channel Memory Architecture
Supports Intel® Extreme Memory Profile (XMP)
* According to Intel® SPEC, the Max. 32GB memory capacity can be supported with DIMMs of 8GB (or above). ASUS will update QVL once the DIMMs are available on the market.
* Refer to www.asus.com or user manual for the Memory QVL (Qualified Vendors Lists).
* Due to OS limitation, when installing total memory of 4GB capacity or more, Windows® 32-bit operation system may only recognize less than 3GB. Install a 64-bit Windows® OS when you want to install 4GB or more memory on the motherboard."
....so it should work fine but maybe a BIOS update may be needed to fully support a later release of RAM capacity or even density RAM Chips. They say they would update 'when available' referring to the 8GB sticks but newer chips on the stick could make it fall under the same update.
Another possibility if they were all recognized originally is to clean off the memory contacts with a clean soft pencil eraser and then pop them in and out of the sockets 5 or 6 times to burnish the contacts.
You have to be a little bit crazy to keep you from going insane.