2GB STICK For HP Compaq DC Series Desktop dc7800 dc7900 Ultra-slim. SO-DIMM DDR2 NON-ECC PC2-6400 800MHz RAM Memory. Genuine A-Tech Brand.Ultra Slim Model 2GB STICK SO-DIMM DDR2 NON-ECC PC2-6400 800MHz RAM Memory Genuine A-Tech Memory Lifetime Warranty Toll Free Technical Support 1-866-557-4527 Designed For HP Compaq DC Series Desktop. (See Compatibility List Below)