4GB KIT 4x 1GB HP Compaq DX Desktop dx2100 dx2280 dx6120 dx7200 Microtower dx7200 Slim Tower dx7400 Microtower dx7400 Small Form Factor DIMM DDR2 NONECC PC2-5300 667MHz RAM Memory Genuine A-Tech Brand 4GB KIT (4 x 1GB) DIMM DDR2 NON-ECC PC2-5300 667MHz RAM Memory Genuine A-Tech Memory Lifetime Warranty Toll Free Technical Support 1-866-557-4527 Designed For HP Compaq DX Series Desktop. (See Compatibility List Below)