DEEP DIVEFour NVIDIA generations side by side
The data-centre GPU has changed more in four years than in the previous decade. Each generation added a lower-precision number format, more memory and a faster scale-up link.
| H100 (2022) | B200 (2024) | B300 (2025) | Rubin (2026) |
| Process | TSMC 4N | TSMC 4NP | TSMC 4NP | TSMC 3 nm-class |
| Dies | 1 | 2 + NV-HBI | 2 | 2 compute + I/O |
| Transistors | 80 B | 208 B | 208 B | 336 B (reported) |
| Memory | 80 GB HBM3 | 192 GB HBM3E | 288 GB HBM3E | 288 GB HBM4 |
| Bandwidth | 3.35 TB/s | 8 TB/s | 8 TB/s | up to 22 TB/s |
| New format | FP8 | FP4 | FP4 (more throughput) | NVFP4 |
| Scale-up | NVLink 4, 900 GB/s | NVLink 5, 1.8 TB/s | NVLink 5 | NVLink 6, 3.6 TB/s |
Memory bandwidth grew about 6.5× from H100 to Rubin and capacity about 3.6×, while low-precision compute grew far more — evidence that the industry is fighting the memory wall with HBM4 and wider packages, not only with more FLOPS.
ANATOMYWhat is inside an AI accelerator die
- Matrix engines (tensor cores, systolic arrays): the bulk of the arithmetic, in FP16/BF16/FP8/FP4.
- Vector and scalar units for activations, normalisation and control.
- On-chip SRAM: register files, shared memory and a large L2 cache (tens of MB) to reuse data.
- Memory controllers and PHYs for HBM along the die edges.
- Scale-up and scale-out I/O: NVLink or equivalent SerDes, PCIe for the host.
- Engines for data movement: DMA and tensor-memory accelerators that copy tiles asynchronously.
- Security and management: root of trust, confidential-computing encryption, telemetry.
TRAINING VS INFERENCETwo different jobs
TrainingHuge matrix multiplies at high arithmetic intensity, backward passes, gradient all-reduce across thousands of chips; limited by compute and interconnect.
Inference prefillProcessing the prompt is compute-bound, similar to training's forward pass.
Inference decodeGenerating one token at a time is memory-bandwidth-bound: every step reads all weights and the KV cache. HBM bandwidth and batching decide throughput.
ConsequenceSome products separate the phases: NVIDIA's Rubin CPX targets prefill with cheaper GDDR7 memory, while HBM parts serve decode.
CUSTOM SILICONHyperscaler accelerators
Cloud companies design their own chips to cut cost and dependence on one supplier: Google's TPUs (now Ironwood, v7), Amazon's Trainium and Inferentia (Trainium2 generally available since late 2024, Trainium3 on a 3 nm-class process), Meta's MTIA and Microsoft's Maia. They are typically designed with partners such as Broadcom, Marvell or Alchip, and built on TSMC processes with CoWoS and HBM — the same supply chain as merchant GPUs.
READING SPECSHow to compare accelerator numbers
- Check the number format: FP4 figures are 2× FP8, which is 2× FP16.
- Check dense versus sparse: sparse figures assume 2:4 structured sparsity and are double the dense ones.
- Divide compute by memory bandwidth to find the ridge point; workloads below it will not reach peak (see the GPU optimization page).
- Compare at system level for large models: a 72-GPU rack with a fast scale-up network behaves very differently from eight GPUs in a server.
- Look for measured results (MLPerf, independent benchmarks) rather than peak numbers.