4GB 1333MHz DDR3; Patriot Memory's Signature Line DDR3 Non-ECC Unbuffered memory delivers quality, reliability and performance expected for today's computer needs. These 4GB modules are designed to run at PC3-10600 (1333MHz) and built using specific build-of-materials (BOMs) we ensure that every module meets and exceeds industry standards: offering you a hassle-free upgrade.