Hi I'm using my Dell Optiplex and it came with 2G memory I changed it to 8G the computer boots fine, works fine but when you check the system info in the memory part it said installed RAM 8.00 GB(3.00 GB usabl) what does that mean? Thanks
Are you running a 32-bit operating system? (Look under System/properties to check). If so, you are limited to 4G, which will often appear as 3G when the RAM used for administrative purposes is deducted.