First time posting a problem of mine in a forum so please forgive me if I am missing some crucial information. I have an asus p8z68-v motherboard. I have an intel i7 in it with a geforce external graphics card. I have 16gb of ram (4*4 sticks bought in one box). This computer has been running without problems for a few years now. I decided today to open it up today and neaten up some of the cables and removed excess dust. I reinstalled windows onto my solid state drive. Now here is where the problem comes in. Both the BIOS and windows say that there is only 8gb of ram installed. But when i go into the asus utilities in the bios it shows all 4 sticks. Now i have removed all the sticks tried different combinations of all 4 and only 2 to see if there was bad RAM without any luck. I have tried reducing the ram speed without any success. This is very frustrating I have tried looking through various sites and have been unable to find a soloution. Now I do have windows 7 proffesional 64 bit. I have had the computer run with all 16gb without problems but for whatever reason I cannot figure out what I have messed up by accident to cause this problem. Thanks for all who take the time to read and reply.