IBM's Power11 Processor Architecture at Hot Chips 2025

Summary

IBM Power Roadmap Third up on today’s CPU track is IBM. Big Blue is at the conference to talk about its latest generation Power architecture chip, the Power11. IBM starts off by recapping Power. Why it exists, and what IBM’s goals are for the processor and architecture. IBM is very system-focused, rather than focusing on selling just CPUs. 1P and 2P systems, all the way up to 16P “glueless” systems. Recapping the Power release history, Power10 has proven to be very successful for IBM, “beyond our wildest dreams.” As a result, Power11 is not a substantial change from Power10; it builds upon Power10 rather than replacing large parts of it. This also means that there’s not as much new here as there have been in past Power presentations – or even other Hot Chips presentations. To note: Power11 systems have already launched. So this Hot Chips presentation is more to bring the crowd up to speed than to blow everyone’s minds with new information. IBM’s philosophy is fewer, larger cores, and then scaling up the number of cores as necessary. One of the big changes coming from Power10? The need to integrate AI into the processor cores. In some respects, IBM was already ahead of the curve here with their matrix multiplication engine in Power10. But, of course, that’s not enough. Power10 was built on Samsung 7LPE. Power11 stays on 7nm (based on feedback from clients), so there was a focus on speed instead of density. As a result, it’s built on a newer iteration of Samsung’s 7nm technology. Power11 also goes to a stacked design. IBM is using a silicon interposer, also based on Samsung fab offerings. Besides making a handful of core architecture changes, there has been a focus on the full system stack for Power11. This means working on everything from quantum safety for resilience against future attacks, up to improving how to go about deploying updates to systems. Power11 OMI Memory Bigger still are the upgrades to the memory subsystem for Power11, which IBM calls their OMI Memo...