The Short Answer
For most ML engineers training models under 30B parameters or running standard fine-tuning workloads, the A100 80GB hits the sweet spot. H100 becomes clearly worth it when you're training 70B+ parameter models, running high-throughput inference at scale, or when wall-clock time is genuinely costing you more than GPU cost.
Specs Comparison: What Actually Matters
| Spec | A100 SXM 80GB | A100 PCIe 80GB | H100 SXM 80GB | H100 PCIe 80GB |
|---|---|---|---|---|
| Architecture | Ampere | Ampere | Hopper | Hopper |
| VRAM | 80 GB HBM2e | 80 GB HBM2e | 80 GB HBM3 | 80 GB HBM2e |
| Memory bandwidth | 2.0 TB/s | 2.0 TB/s | 3.35 TB/s | 2.0 TB/s |
| BF16 TFLOPS | 312 | 312 | 989 | 756 |
| FP8 TFLOPS | — | — | 1,979 | 1,513 |
| NVLink | 3rd gen (600 GB/s) | — | 4th gen (900 GB/s) | — |
| TDP | 400W | 300W | 700W | 350W |
The headline numbers: H100 SXM has 3.2× the BF16 compute and 67% more memory bandwidth than the A100 SXM. On paper, it's a significant leap. In practice, your training loop won't always saturate these theoretical limits.
Real-World Training Speed
Here's what the performance difference actually looks like for common ML workloads, based on benchmarks from ML infrastructure teams:
| Workload | A100 80GB (time) | H100 80GB (time) | Speedup |
|---|---|---|---|
| Llama 3 8B fine-tuning (1 GPU) | 100% | ~60% | 1.6× |
| Llama 3 70B pre-training (8 GPU) | 100% | ~40% | 2.4× |
| SDXL image generation | 100% | ~55% | 1.8× |
| GPT-4 class training (large cluster) | 100% | ~35% | 2.8× |
| Embedding model fine-tuning | 100% | ~70% | 1.4× |
Approximate values. Actual speedup depends on model architecture, batch size, and optimizer.
The H100 shines most in large-scale multi-GPU training thanks to NVLink 4th gen, and in throughput-heavy inference where FP8 precision and higher bandwidth pay off. For single-GPU fine-tuning of 7B–13B models, the speedup is a more modest 1.4–1.6×.
Cloud Pricing: What You'll Actually Pay
These are current (April 2026) on-demand prices from major GPU cloud providers:
| Provider | A100 40GB/h | A100 80GB/h | H100 PCIe/h | H100 SXM/h |
|---|---|---|---|---|
| Vast.ai† | $0.55 | $0.79 | — | $1.89 |
| RunPod | — | $1.59 | — | $2.49 |
| Lambda Labs | $1.10 | $1.50 | $2.49 | $3.99 |
| CoreWeave | $1.99 | $2.21 | — | $4.30 |
| Google Cloud | $2.48 | $3.67 | — | $8.10 |
| AWS (p4d.24xl) | $3.97 (8× A100) | — | $12.29 | |
† Interruptible / spot pricing. Prices exclude storage and egress. Verified April 2026.
The Price-Performance Math
Let's say you're training a Llama 3 70B model and have an A100 SXM job that takes 100 hours on Lambda Labs at $1.50/h = $150 total.
On H100 SXM (Lambda), the same job finishes in ~42 hours at $3.99/h = $167.58. You're paying more in absolute terms, and only saving 58 hours. If your time is worth more than $0.30/hour saved (spoiler: it usually is), the H100 makes sense for jobs running this long.
For a 5-hour fine-tune of a 7B model on Lambda A100 ($1.10/h): $5.50 total. On H100 PCIe ($2.49/h) finishing in ~3.5h: $8.72 total. Here, A100 wins clearly — you're paying 59% more for a 1.4× speedup.
When to Choose H100
- Training 70B+ parameter models — where multi-node NVLink speed matters
- Production inference at high throughput — H100's FP8 and Flash Attention 3 support delivers 2–3× better tokens/second
- Time-critical experiments — when iteration speed matters more than cost per run
- Very long training runs — where the H100's speedup compresses calendar time enough to offset price
- FP8 quantized training — A100 doesn't support FP8; H100 can train large models faster at lower precision
When A100 is the Better Choice
- Fine-tuning 7B–30B models — A100 80GB has enough VRAM and the 1.4–1.6× speedup doesn't justify H100's price
- Budget-sensitive research — A100 on Lambda is 55–60% cheaper than H100 SXM
- Stable Diffusion / image generation — A100 80GB is already fast enough; H100 gives modest gains
- Embedding models and fine-tuning — throughput gains are small; A100 wins on cost
- Iterative prototyping — run more experiments with an A100 budget than fewer experiments on H100
Verdict
For most ML engineers, start with A100 80GB. It's the sweet spot of VRAM capacity, price, and availability in 2026. Once you've validated your training setup and need to scale, or when training time itself becomes the bottleneck, upgrade to H100.
The RunPod community cloud and Vast.ai offer the cheapest A100s (from $0.79/h interruptible), while Lambda Labs offers the most reliable on-demand A100 and H100 access with SSH in seconds.
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