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AMD MI455X: From Launch to Early Benchmarks
AMD launched the rack-scale AI-focused Instinct MI455X with 432GB of HBM4, followed immediately by early benchmarks revealing a massive 23.3TB/s memory bandwidth.
2026-07-24 ~ 2026-07-24 · 2 episodes · 4 posts
Episode 1 · AMD Unveils MI455X with 432GB HBM4 for Rack-Scale AI (2026-07-24, 2 posts)
AMD introduced the Instinct MI455X GPU designed for rack-scale AI, featuring 432GB of HBM4 memory that exceeds the combined total of five H100s. The ROCm ecosystem is already being updated to support developers with this new high-bandwidth architecture.
- AMD MI455X Architecture Breakdown: First Rack-Native GPU with HBM4 — ryanshrout · 2026-07-24
- AMD’s MI455X brings 432GB of HBM4 per GPU and day-one ROCm support — LysandreJik · 2026-07-24
Episode 2 · AMD MI455X Early Tests Reveal 23.3TB/s HBM4 Bandwidth (2026-07-24, 2 posts)
Early tests of AMD's MI455X show it features 432GB of HBM4 with a peak bandwidth of 23.3TB/s. However, its pin speed of 7.5 Gbps lags behind Nvidia's reported 10.7 Gbps.
- AMD’s HBM4 data rate trails Nvidia’s 10.7 Gbps per pin claim — zephyr_z9 · 2026-07-24
- AMD's MI455X reportedly delivers 432GB of HBM4 and 23.3TB/s bandwidth — art_zucker · 2026-07-24