Specifications: MI250 128GB vs MI300X 192GB
The MI250 128GB and MI300X 192GB represent different generations of GPU architecture for AI workloads. Memory capacity ranges from 128GB to 192GB, with significant differences in memory bandwidth, compute throughput (FP8/FP16/TF32), NVLink connectivity, and TDP. The MI300X 192GB supports newer technologies like FP8 transformer engines, fourth-gen tensor cores, and higher-bandwidth HBM3e or HBM4 memory.
AI Inference Performance
For LLM inference, the MI300X generally achieves 30-120% higher throughput than the MI250 depending on model size and batch configuration. For a 7B model at FP8 with continuous batching, the MI250 serves 1,800-2,400 tok/s while the MI300X reaches 3,000-5,000 tok/s. For 70B models, tensor parallelism across 4 GPUs is needed on the MI250 while the MI300X may serve the same model with 2 GPUs due to higher VRAM. Prefill latency for 4K tokens ranges from 35-55ms for the MI250 versus 18-35ms for the MI300X.
Training Throughput Comparison
On training workloads, the MI300X delivers 40-120% higher throughput for typical model sizes. For a 7B model at BF16 mixed precision, per-GPU throughput reaches 3,500-4,500 tok/s on the MI250 versus 5,000-8,000 tok/s on the MI300X. Model FLOPS utilization (MFU) ranges from 38-48% on the MI250 and 42-55% on the MI300X. Memory capacity constraints on the MI250 require activation checkpointing for models larger than 13B, while the MI300X accommodates larger models without checkpointing.
VRAM and Model Capacity Analysis
Memory capacity is the most critical differentiator. The MI250 128GB has 128GB VRAM, while the MI300X 192GB has 192GB VRAM. At FP16, a 7B model requires ~14 GB for weights, plus KV cache of ~1.5 GB per 128K context per request. INT4 quantization halves the weight memory requirement, enabling larger models or batch sizes. The VRAM gap is most impactful for long-context serving and large batch inference.
Cloud Pricing and TCO
On-demand cloud pricing for the MI250 averages $1.50/hr while the MI300X averages $2.20/hr. However, cost-per-token analysis often favors the MI300X by 15-40% for sustained production workloads due to higher throughput. Reserved 12-month contracts provide 30-50% discounts. For a 64-GPU, 3-year TCO, the MI250 cluster costs $815K-$933K while the MI300X cluster costs $1376K-$1335K including hardware, power, cooling, and maintenance.
Which GPU Should You Choose?
Choose the MI250 for: budget-constrained deployments, models under 13B that fit in available VRAM, batch inference workloads where throughput per dollar is secondary to absolute cost, and development/staging environments. Choose the MI300X for: production serving at scale, models larger than 13B parameters, workloads requiring FP8/FP4 precision, long-context inference beyond 128K tokens, and clusters above 128 GPUs where scaling efficiency matters.