AH405A-PCW is a HP Compatible 32GB [4x 8GB] PC2-4200 DDR2-533 4Rx4 Registered RDIMM Memory Kit (HP PN# AH405A). This is a 'major brand' module kit (from either Samsung, Micron, Hynix, Infineon, etc.), equivalent in every way to HP original memory. All PCW modules meet or exceed OEM specifications and JEDEC standards.