AMD Unveils Instinct MI455X Flagship Accelerator

AMD introduced the MI455X accelerator at Advancing AI 2026, featuring 320 billion transistors and 432GB of HBM4 memory for AI workloads.

The AMD Instinct MI455X, revealed at the Advancing AI 2026 event, is a flagship accelerator built on the CDNA5 architecture. It integrates 320 billion transistors using TSMC N2 for its eight XCDs and TSMC N3P for its FCDs and IODs. Utilizing CoWoS-L and SoIC-Stacking, the package includes 12 HBM4 stacks providing 432GB of memory and 23.3TB/s bandwidth. The MI455X features 256 active WGPs clocked at 2.4GHz, with each XCD containing two Shader Engines. AMD has replaced Infinity Cache with 192MB of shared L2 cache across two FCDs. Positioned to compete with Nvidia’s Rubin architecture and Vera Rubin NVL72, the MI455X precedes the MI500 and MI600 scheduled for 2027 and 2028.