A40 vs Instinct MI250X
NVIDIA A40 (Ampere, 48 GB) against AMD Instinct MI250X (CDNA 2, 128 GB): memory, compute, power and rental price, compared for LLM inference and training.
Pick two GPUs to compare
Side-by-Side Specifications
| Spec | A40 | Instinct MI250X |
|---|---|---|
| Architecture | Ampere | CDNA 2 |
| Memory | 48 GB GDDR6 | 128 GB HBM2e |
| Memory bandwidth | 696 GB/s | 3,277 GB/s |
| FP16 tensor compute | 299.4 TFLOPS | 383 TFLOPS |
| INT8 tensor compute | 598.7 TOPS | 383 TOPS |
| Interconnect | NVLink 3.0 · 112.5 GB/s | Infinity Fabric 3 · 800 GB/s |
| TDP | 300 W | 560 W |
| Est. on-demand price | ~$1.80/h | ~$2.50/h |
| FP16 TFLOPS per $/h | 166 | 153 |
Highlighted values indicate the stronger spec. Hourly rates are indicative on-demand estimates.
Verdict
Raw performance: The Instinct MI250X leads on FP16 tensor compute (1.3x advantage), which translates directly into higher token throughput for inference and shorter training steps.
Memory: With 128 GB per card, the Instinct MI250X fits larger models on fewer GPUs — fewer cards means less inter-GPU communication and simpler deployments.
Value: At current on-demand rates, the A40 delivers more compute per dollar (166 vs 153 FP16 TFLOPS per $/h). If your model fits in its VRAM budget, it is usually the more economical choice.
GPUs Needed for Popular LLMs
Cards required to serve each model at 8-bit quantization (with 20% overhead for activations and KV cache).
| Model | VRAM (8-bit) | A40 | Instinct MI250X |
|---|---|---|---|
| GPT-5.6 Sol | 2682 GB | 56x | 21x |
| DeepSeek V4 Pro (671B) | 750 GB | 16x | 6x |
| Muse Spark 1.1 | 335 GB | 7x | 3x |
| Claude 5 Sonnet (175B) | 196 GB | 5x | 2x |
| Nova Premier (80B) | 89 GB | 2x | 1x |
| Nova Core (34B) | 38 GB | 1x | 1x |
| Nova Lite (12B) | 13 GB | 1x | 1x |
| Phi 3.5 (3.8B) | 4 GB | 1x | 1x |
Frequently Asked Questions
Which is better for LLM inference: A40 or Instinct MI250X?
The Instinct MI250X delivers more raw FP16 compute (383 TFLOPS) and the Instinct MI250X offers the most memory per card (128 GB). For cost-efficiency, the A40 currently gives more FP16 TFLOPS per dollar of on-demand rental (166 vs 153 TFLOPS per $/h).
How much more memory does the Instinct MI250X have?
The A40 has 48 GB of GDDR6 versus 128 GB of HBM2e for the Instinct MI250X — a ratio of 2.67x in favor of the Instinct MI250X. More VRAM per card means fewer GPUs to fit a given model.
Is the A40 or the Instinct MI250X cheaper to rent?
Estimated on-demand rates are ~$1.80/h for the A40 and ~$2.50/h for the Instinct MI250X. Raw hourly price is only part of the story: normalize by throughput (TFLOPS per $/h) and by how many cards you need for your model's VRAM.
How do the A40 and Instinct MI250X compare on power?
The A40 has a TDP of 300W versus 560W for the Instinct MI250X. FP16 compute per watt: 1.0 vs 0.7 TFLOPS/W.
Deploy on a GPU cloud
Rent the A40 or Instinct MI250X by the hour instead of buying hardware.
