A-TECH 8GB KIT (2 x 4GB) for HP-Compaq Workstation Series xw6400 xw6600 xw8400 xw8600. DIMM DDR2 ECC Fully Buffered PC2-5300 667MHz RAM Memory. Genuine Brand. 8GB KIT (2 x 4GB) DIMM DDR2 ECC Fully Buffered PC2-5300 667MHz RAM Memory Genuine A-Tech Memory Lifetime Warranty Toll Free Technical Support 1-866-557-4527 Designed For HP-Compaq Workstation Series. (See Compatibility List Below)