2GB 240-pin PC2-5300 DDR2-667 non-ECC non-Registered DIMM. Genuine CMS brand, CMS is one of the most trusted names in the Computer Memory industry and this product carries a Lifetime Warranty from CMS Compatible with: Dell OptiPlex 210L 320 330 740 745 755 Maximum Memory: 4 or 8GB Expansion: 4 or 2 Sockets MODULES MAY BE INSTALLED ONE AT A TIME; however, they must be added in like pairs to take advantage of Dual Channel Mode. If 4GB is installed, the recognized memory may be reduced to 3.5GB or less (depending on system configuration and memory allocation). A 64-bit operating system is required to utilize more than 4GB of memory.