AMD MI455X
AMD Instinct MI455X is AMD's next-generation AI GPU announced at CES 2026, belonging to the Instinct MI400 series flagship model, built on CDNA 5 architecture with 2nm and 3nm hybrid process, equipped with 432GB HBM4 memory, delivering 40 PFLOPS FP4 compute, with performance 10× that of the previous-generation MI355X.
Key Specifications
| Specification | Value |
|---|---|
| GPU Architecture | CDNA 5 architecture |
| Process Node | 2nm and 3nm hybrid (TSMC CoWoS-L packaging) |
| Transistor Count | 320 billion |
| GCD Configuration | 2 graphics compute dies (GCDs) |
| MCD Configuration | 2 memory controller dies (MCDs) |
| FP4 Compute | 40 PFLOPS |
| FP8 Compute | 20 PFLOPS |
| FP16 Compute | Estimated ~10 PFLOPS |
| FP32 Compute | Estimated ~5 TFLOPS |
| INT8 Compute | Estimated ~80 PFLOPS |
| Memory Capacity | 432 GB |
| Memory Type | HBM4 |
| Memory Sites | 16 HBM4 memory sites |
| Memory Bandwidth | 19.6 TB/s |
| Interconnect | 5th-gen Infinity Fabric (3.6 TB/s) |
| TDP | Not disclosed (estimated 1,500-2,000W) |
| Release Date | January 6, 2026 |
| Mass Production | Second half of 2026 |
| Pricing | Not disclosed |
Architecture & Specifications
MI455X adopts a multi-chip module (MCM) design, with the core comprising:
- 2 graphics compute die (GCD)
- 2 memory controller die (MCD)
- 16 HBM4 memory stacks
Key Technical Innovations
-
CDNA 5 Architecture
- Optimized for low-precision workloads
- Supports FP4, FP8, and BF16 compute
- Performance 10× MI355X
-
5th-Generation Infinity Fabric Interconnect
- Single-node vertical scaling bandwidth up to 3.6 TB/s
- Horizontal scaling bandwidth between nodes up to 300 GB/s
-
HBM4 Memory
- 432GB capacity (1.5× NVIDIA Rubin R200's 288GB)
- 19.6 TB/s bandwidth (89% of NVIDIA Rubin R200's 22 TB/s)
Performance Comparison
| Comparison | MI355X | MI455X | Improvement |
|---|---|---|---|
| FP4 Compute | ~4 PFLOPS | 40 PFLOPS | 10× |
| Memory Capacity | 288GB HBM3e | 432GB HBM4 | 1.5× |
| Memory Bandwidth | ~8 TB/s | 19.6 TB/s | 2.45× |
MI400 Series Models
MI455X belongs to the AMD Instinct MI400 series, which also includes:
- MI455X: For large-scale AI training and inference (flagship)
- MI430X: Supports FP64 double-precision compute (HPC scenarios)
- MI440X: Designed for local enterprise AI (entry-level)
Companion Platform: Helios Rack
Helios Rack Configuration
- 72× MI455X GPUs
- 18× EPYC Venice CPUs (Zen 6, 256 cores)
- Total Memory: 31 TB HBM4
- Total Bandwidth: 1.4 PB/s
- AI Inference Compute: 2.9 FP4 exaFLOPS
- AI Training Compute: 1.4 FP8 exaFLOPS
- TDP: ~300kW (full liquid cooling required)
- Release Date: January 2026
- Mass Production: Second half of 2026
Helios Supporting Hardware
- CPU: AMD EPYC Venice (Zen 6, 2nm, 256 cores)
- NIC: AMD Pensando Vulcano 800G AI NIC
- Interconnect: Infinity Fabric, UALink, Ultra Ethernet
- Network Adapters: Pensando Pollara 400G, Vulcano 800G
Mass Production & Delivery
- Release Date: January 6, 2026 (CES 2026)
- Mass Production: Second half of 2026
- Helios System: Officially launched in second half of 2026
- AMD Official Statement: Helios AI system development progress is on schedule, will be launched as planned in second half of 2026
Application Scenarios
MI455X targets large-scale AI training and distributed inference, suitable for:
- Trillion-parameter LLM training
- High-performance AI inference (low latency, high throughput)
- Reinforcement learning (RL) and agentic AI
- Scientific computing and HPC