RAM not recognised - faulty mobo or?
Win 7 64 pro, Asus Rampage III Extreme.
a total of 6 dimm slots (3 red, 3 black), one black is blocked by internal assembly.
Originally came with 3x 4gb sticks - was working as 12gb fine.
Recently i wanted to upgrade it a bit. MB supports a total of 24gb, so i got myself 2x 4gb sticks, to fill the remaining 2 open slots.
3 R were filled with original 4gb sticks, so i put my 2 new ones in the 2 open B spots. However, when PC booted up, the RAM remained at 12gb.
To test, i removed the original sticks, and placed new ones in their slots (1 and 2 red) - PC recognised 8gb fine.
When i placed the new sticks into 1 and 2 black, however, the PC refused to boot.
Which leads me to believe that for some reason the black slots on my MB are not working or are disabled.
Any way to check/fix this? Or does it mean broken motherboard?