Did you use crucial's "memory configurator" software on their website for your specific dell system? If not, then you may be out of luck. Dell boards can be picky about ram, and dell rarely goes to the trouble of updating a bios for any of it's systems. Oem boards are different from off the shelf boards by asus, gigabyte, msi, etc. Those companies and most others will address ram and cpu issues with bios updates, but dell, gateway and hp rarely do. They aren't designed for upgrading; they would rather have you buy a brand new system.