IBM Power Systems Overview
IBM Power Systems is the hardware brand IBM introduced in 2008 to unify its Power-processor-based servers, replacing the earlier System i and System p lines. It is the hardware platform that runs IBM i, AIX, and Linux workloads today, including the modern successors to AS400 environments.
IBM Power Systems is the hardware brand IBM has used since 2008 for its Power-processor-based server line. It is the current hardware platform for organizations running IBM i, the operating system that traces its lineage directly back to the original AS400. Anyone researching an AS400, iSeries, or System i environment today is, in practical terms, researching an IBM Power Systems upgrade path.
What Is IBM Power Systems?
IBM Power Systems is IBM's family of enterprise server hardware built around its own POWER processor architecture. Unlike x86 servers, IBM designs the POWER chip, the firmware, and (for IBM i workloads) much of the operating system stack itself, which is part of why IBM i shops describe the platform as tightly integrated. IBM Power Systems hardware runs three operating systems: IBM i, AIX (IBM's UNIX), and Linux.
The brand covers a range of hardware, from single-socket entry servers sized for small IBM i environments up to large scale-up systems designed for enterprise workloads across all three operating systems on the same physical chassis or data center footprint.
IBM Power Systems Brand History
IBM Power Systems was introduced in 2008 when IBM merged its two separate mid-range and UNIX hardware brands, System i and System p, into a single hardware family. At the same time, IBM split the AS400 operating system away from the hardware brand entirely: the OS became IBM i, and the hardware became IBM Power Systems. This closed out a decade of renaming that had run from AS400 (1988) to iSeries (2000) to System i (2006) to today's naming.
IBM Power Processor Generations
IBM has released a new POWER processor generation roughly every three to four years since the Power Systems brand launched. Broadly, the generations relevant to current IBM i environments are POWER7 (2010), POWER8 (2014), Power9 (2017), Power10 (2021), and Power11, announced July 8, 2025. Each generation has generally delivered higher CPW per core, more memory bandwidth, and improved energy efficiency than the one before it. Organizations on Power8 or earlier hardware are typically well past the point where an upgrade evaluation makes sense, since IBM support windows and IBM i OS compatibility both narrow as a generation ages.
Operating Systems on IBM Power
IBM i is the operating system most closely associated with AS400 heritage. It descends directly from OS/400, the original AS400 operating system, and preserves backward compatibility for RPG, COBOL, and CL applications going back decades. AIX is IBM's UNIX operating system, also built for POWER hardware. Linux on Power runs standard Linux distributions compiled for the POWER architecture. A single Power Systems server can, depending on model and configuration, run partitions of more than one of these operating systems side by side.
How IBM Power Systems Relates to AS400
There is no current hardware line called AS400. Organizations that still say "our AS400" are, in almost every case, describing an IBM i workload that either still runs on aging Power hardware or needs to move to current IBM Power Systems hardware such as Power10 or Power11. See AS400 model history for the AS400-era hardware itself, and IBM Power11 overview for the current generation.