Memory Only Showing 4GB when 8GB is installed

Solution
The only thing I could suggest then is to download the latest bios firmware available for your board use the asus renaming tool also provided.

Put the bios file on a usb flash drive.
Take out all of your memory sticks.
Insert the usb flash drive into the designated usb port of the board for the flash back procedure
Press your flash back key on the motherboard and wait for the bios to be flashed or updated from the usb flash drive to the bios.
Once done. Manually reset the bios back to factory defaults via the jumper on the motherboard.
Power the system completely off and insert the memory sticks back into the motherboard.
And power the system up.

I think looking at it, it must be a bug in the bios.
And this is the way I would do it...
Well take one stick out and test it in the first memory slot of your motherboard.

If the bios still reads 4Gb of memory.
Take that stick out and place the other 4Gb memory stick in the first slot again.
See if the bios reads that 4gb of memory.

The likely cause memory not seated right in one of the slots.
A memory stick has gone bad, and the bios cannot read it.

Or one of your memory slots it`s self has broken or is damaged and it cannot read the memory stick inserted into it.
Check that both memory modules are seated flush in the slots and the locking tabs at each side are engaged.
 
The only thing I could suggest then is to download the latest bios firmware available for your board use the asus renaming tool also provided.

Put the bios file on a usb flash drive.
Take out all of your memory sticks.
Insert the usb flash drive into the designated usb port of the board for the flash back procedure
Press your flash back key on the motherboard and wait for the bios to be flashed or updated from the usb flash drive to the bios.
Once done. Manually reset the bios back to factory defaults via the jumper on the motherboard.
Power the system completely off and insert the memory sticks back into the motherboard.
And power the system up.

I think looking at it, it must be a bug in the bios.
And this is the way I would do it to clear it if the system constantly halts with a memory initialization error, then hangs or boot loops.
Cannot think of much else apart from trying two totally new ram sticks.

I`m presuming it is an ASUS branded motherboard.
 
Solution