This Cisco MEM-3900-1GU2GB compatible 2GB (2x1GB) factory original DRAM is 100% guaranteed to be compatible with your system and to work right the first time. Adding additional memory is the best way to increase the performance of your system. All memory is built to strict JEDEC standards to meet or exceed the Tier 1 OEM's factory requirements. The products are also guaranteed by federal law to not affect or void OEM warranties.