is probably the only post in that thread you need to read, unless you want to know more about the gory details.
The key point: your motherboard needs to support "memory remapping" or "hoisting" and it needs to be turned on in the BIOS. To even have this option you may need to flash a later BIOS if the one in your board is a fairly early one. However, the option may not be exposed, or it may not be available at all. It clearly isn't turned on now, so you need to go look in your BIOS and see if you can see something like that (unfortunately it gets named various things and put in various places). If you can't find anything, and there's a newer version of the BIOS for your board available, flashing that might
give you the option (or it may just silently turn it on without exposing it in the BIOS menus). However, it's also possible that this board just does not support this feature, period. Only somebody else who has already tried all this with that particular board, or something definitive in specs or a FAQ at ASUS, can tell you for sure.