Arch Memory 2 GB (1 x 2 GB) 240-Pin DDR3 UDIMM for HP Pavilion p6531p RAM Arch Memory is a Registered Trademark of Arch Computer, LLC 2GB 240-Pin DDR3 1333Mhz SDRAM Compatible with systems that use 240Pin PC-10600 SDRAM modules 2 GB Memory for HP Pavilion p6531p By Arch Memory Lifetime Warranty