The IBM System x3950 is built on IBM X3 Architecture that delivers mainframe-inspired enhancements to the high-performance x86 server industry. With a balanced focus on providing breakthrough 64-bit performance and high availability, the x3950 is designed for the changing business needs of enterprise customers - at a low entry price point.This x3950 model comes with a 4-socket license of Windows Server 2003 R2 Datacenter Edition.