My Mountain Lion iMac is having some problems. I have 12GB of RAM in my computer, but it only displays 4GB. Here is the thing. At first it showed the full 12GB. Then, it started showing 6GB so I pulled out the RAM and rearranged it. After it rearranging it, it shows 4GB. I'm not sure if this is the right section for this, but I really need help.
Bring it to an Apple reseller they will help you.