Corsair 1600

6 GB [2 GB X3] DDR3-1600 Triple Memory Module Corsair

im running windows 7 64bit and it only shows 2gbs ... what is going on

Start | Type msconfig in the "Start Search" field, and hit ENTER | Configuration Utility--> "Boot" tab | "Advanced options" button | Under the "BOOT Advanced Options" dialog, make sure the "Maximum memory" option isn't checked. If it is checked, uncheck it and reboot.