AMD's Instinct MI455X GPUs extend the company's AI roadmap, bringing leading HBM4 capacities and over 40 PFLOPs of compute for Agentic AI, rivaling NVIDIA's Rubin chip.
AMD Has An Answer To NVIDIA's Rubin, It's Called Instinct MI455X & It's An Engineering Marvel For Agentic AI With More HBM4 Than Any Other AI Chip On The Planet
The AMD Instinct MI455X is the GPU that will power the Helios AI rack. This GPU is based on the latest CDNA 5 architecture, and packs 320 billion transistors, just 16 billion transistors shy of the NVIDIA Rubin chip. MI455X is designed to offer:
- Purpose-Built AI Infrastructure: The AMD Instinct MI400 Series portfolio includes the AMD Helios rack-scale solution powered by AMD Instinct MI455X GPUs for frontier AI and AI factory deployments alongside AMD Instinct MI430X GPUs for sovereign AI and HPC. Together, the portfolio provides purpose-built solutions optimized for hyperscale AI factories, national infrastructure, research institutions and leadership-class HPC environments.
- Leadership Performance Across AI and HPC: AMD Instinct MI455X GPUs deliver the compute, memory and networking performance required for high-volume inference, frontier-model training and fine-tuning. AMD Instinct MI430X GPUs deliver uncompromised accuracy and throughput across converged AI and HPC workflows with up to 288 TFLOPS of hardware-based FP64 performance for scientific computing. Across the portfolio, industry-leading HBM4 memory and high memory bandwidth help customers support larger models, reduce infrastructure complexity and improve efficiency at scale.
- Open Software Foundation: Powered by AMD ROCm software, the MI400 Series provides an open software foundation with programming models, compilers, libraries, runtimes and deployment tools for AI and HPC. This commitment to open standards supports interoperability and long-term portability across software, system and networking choices, helping customers innovate without vendor lock-in.
- Secure and Scalable by Design: AMD Instinct MI400 Series GPUs incorporate advanced security capabilities, secure boot, encrypted GPU-to-GPU links and hardware-based protections to help safeguard sensitive AI and HPC workloads. Combined with scalable system architectures – from the AMD Helios rackscale solution for frontier AI to traditional mesh-based HPC deployments – AMD Instinct MI400 series GPUs enable customers to deploy AI infrastructure with flexibility, confidence and long-term operational consistency.
For the Instinct MI400 series, AMD will have three products; the first two are the Instinct MI455X & the MI450X, which are aimed at scale AI Training & Inference workloads. The MI455X is powering the Helios rack. There's also a cost-optimized 6-HBM variant.
The third chip is the MI430X, which is aimed at HPC & Sovereign AI workloads, featuring the "highest performance" FP64 capabilities, hybrid compute (CPU+GPU), and the same HBM4 memory as the MI455X.
The AMD Instinct MI455X is a 40 PFLOPs of FP4 & 20 PFLOPs FP8 compute, which is double the compute capability of the MI350 series, making it a disruptive offering for AI. For comparison, an NVIDIA Rubin GPU offers 50 PFLOPs of FP4 and 17.5 PFLOPs of FP8 compute.
In addition to the compute capability, AMD is also going to leverage HBM4 memory for its Instinct MI400 series. The new chip will offer a 50% memory capacity uplift from 288GB HBM3e to 432GB HBM4. The HBM4 standard will offer a massive 19.6 TB/s bandwidth, more than double that of the 8 TB/s for the MI350 series. For comparison, the Rubin GPU comes with 288 GB of HBM4 at 22 TB/s.
AMD has positioned its Instinct MI400 GPUs against NVIDIA's Vera Rubin, and the high-level comparison looks something like the following:
- 1.5x Memory Capacity vs Competition
- Same Memory Bandwidth vs Competition
- Same FP4 / FP8 FLOPs vs Competition
- Same Scale-Up Bandwidth vs Competition
- 1.5x Scale-Out Bandwidth vs Competition
For the MI400 series, there will be two products; the first one is the Instinct MI455X, which is aimed at scale AI Training & Inference workloads. The other one is MI430X, which is aimed at HPC & Sovereign AI workloads, featuring hardware-based FP64 capabilities, hybrid compute (CPU+GPU), and the same HBM4 memory as the MI455X.
In 2027, AMD will be introducing its next-gen Instinct MI500 series AI accelerators. Since AMD is shifting to an annual cadence, we are going to see updates on the datacenter and AI front at a very rapid pace, similar to what NVIDIA is doing now with a standard and an "Ultra" offering. These will be used to power the next-gen AI racks and will offer a disruptive uplift in overall performance.
According to AMD, the Instinct MI500 series will offer next-gen compute, memory, and interconnect capabilities.
AMD Instinct AI Accelerators:
| Accelerator Name | AMD Instinct MI500 | AMD Instinct MI400 | AMD Instinct MI350X | AMD Instinct MI325X | AMD Instinct MI300X | AMD Instinct MI250X |
|---|---|---|---|---|---|---|
| GPU Architecture | CDNA 6 | CDNA 5 | CDNA 4 | Aqua Vanjaram (CDNA 3) | Aqua Vanjaram (CDNA 3) | Aldebaran (CDNA 2) |
| GPU Process Node | 2nm | 2nm+3nm | 3nm | 5nm+6nm | 5nm+6nm | 6nm |
| XCDs (Chiplets) | TBD | 8 (MCM) | 8 (MCM) | 8 (MCM) | 8 (MCM) | 2 (MCM) 1 (Per Die) |
| GPU Cores | TBD | 18,000+ | 16,384 | 19,456 | 19,456 | 14,080 |
| GPU Clock Speed (Max) | TBD | TBD | 2400 MHz | 2100 MHz | 2100 MHz | 1700 MHz |
| INT8 Compute | TBD | TBD | 5200 TOPS | 2614 TOPS | 2614 TOPS | 383 TOPs |
| FP6/FP4 Matrix | TBD | 40 PFLOPs | 20 PFLOPs | N/A | N/A | N/A |
| FP8 Matrix | TBD | 20 PFLOPs | 5 PFLOPs | 2.6 PFLOPs | 2.6 PFLOPs | N/A |
| FP16 Matrix | TBD | 10 PFLOPs | 2.5 PFLOPs | 1.3 PFLOPs | 1.3 PFLOPs | 383 TFLOPs |
| FP32 Vector | TBD | TBD | 157.3 TFLOPs | 163.4 TFLOPs | 163.4 TFLOPs | 95.7 TFLOPs |
| FP64 Vector | TBD | TBD | 78.6 TFLOPs | 81.7 TFLOPs | 81.7 TFLOPs | 47.9 TFLOPs |
| VRAM | HBM4E | 432 GB HBM4 | 288 GB HBM3e | 256 GB HBM3e | 192 GB HBM3 | 128 GB HBM2e |
| Infinity Cache | TBD | TBD | 256 MB | 256 MB | 256 MB | N/A |
| Memory Clock | TBD | TBD | 8.0 Gbps | 5.9 Gbps | 5.2 Gbps | 3.2 Gbps |
| Memory Bus | TBD | TBD | 8192-bit | 8192-bit | 8192-bit | 8192-bit |
| Memory Bandwidth | TBD | 23.3 TB/s | 8 TB/s | 6.0 TB/s | 5.3 TB/s | 3.2 TB/s |
| Form Factor | TBD | EAM | OAM | OAM | OAM | OAM |
| Cooling | TBD | Passive / Liquid | Passive / Liquid | Passive Cooling | Passive Cooling | Passive Cooling |
| TDP (Max) | TBD | TBD | 1400W (355X) | 1000W | 750W | 560W |
About the author: A Software Engineer by training and a PC enthusiast by passion, Hassan Mujtaba serves as Wccftech's Senior Editor for hardware section. With years of experience in the industry, he specializes in deep-dive technical analysis of next-generation CPU and GPU architectures, motherboards, and cooling solutions. His work involves not only breaking news on upcoming technologies but also extensive hands-on reviews and benchmarking.
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