Qwen3.8 27B (VLM) at FP8 (E4M3) needs 27.8 GB for its weights and 33.3 GB in total at 8K context with 8 concurrent users. That means it needs 2× RTX 5090 32GB. Every figure is computed by tokcalc's open-source capacity model.
RTX 5090 32GB has no NVLink, so 2-way tensor parallelism runs over PCIe. tokcalc applies a flat 0.85× multi-GPU efficiency factor for this, which is realistic for NVLink-equipped datacenter cards but optimistic for PCIe scale-out — treat the throughput and cost figures for this configuration as an upper bound, and measure before committing.
| GPUs | Total VRAM | VRAM needed | Decode tok/s | Aggregate tok/s | TTFT | Cost / 1M tok | Fits? |
|---|---|---|---|---|---|---|---|
| 1× RTX | 32 GB | 33.3 GB | 0.000 | 0.000 | — | — | ✗ |
| 2× RTX | 64 GB | 33.3 GB | 106.9 | 2566 | 4.37 s | $0.1083 | ✓ |
| 4× RTX | 128 GB | 33.3 GB | 213.8 | 10264 | 2.20 s | $0.0541 | ✓ |
| 8× RTX | 256 GB | 33.3 GB | 427.7 | 41056 | 1.12 s | $0.0271 | ✓ |
| Context | Concurrent users | KV per request | Fits? |
|---|---|---|---|
| 4K | 86 | 1.07 GB | ✓ fits |
| 8K | 52 | 2.15 GB | ✓ fits |
| 33K | 15 | 8.59 GB | ✓ fits |
| 66K | 8 | 17.18 GB | ✓ fits |
| 131K | 4 | 34.36 GB | ✓ fits |
| GPU | GPUs | Aggregate tok/s | Cost / 1M tok |
|---|---|---|---|
| AMD MI300X 192GB | 1× | 2232 | $0.3111 |
| A100 40GB SXM4 | 1× | 652.8 | $0.3830 |
| AMD MI325X 288GB | 1× | 2527 | $0.3847 |
| A100 80GB SXM4 | 1× | 842.3 | $0.3957 |
| Intel Gaudi 3 128GB | 1× | 1390 | $0.3997 |
| H100 SXM5 80GB | 1× | 1411 | $0.4922 |
Yes, but it needs 2× RTX 5090 32GB. At FP8 (E4M3) the total footprint is 33.3 GB (27.8 GB of weights plus 5.5 GB of KV cache at 8K × 8 concurrent users), against 64 GB of available VRAM across 2 GPUs.
106.9 tokens/sec per stream and 2566 tok/s aggregate with continuous batching at 8 concurrent users. Time to first token is 4.37 s, and inter-token latency is 9.4 ms.
$0.1083 per 1M output tokens at 2× RTX 5090 32GB ($0.5000/hr). That is the marginal hardware cost — add idle capacity, ops, and egress for the real figure.
27.8 GB for the weights at FP8 (E4M3), plus 5.5 GB of KV cache for 8 concurrent requests at 8K context — 33.3 GB total. Every extra concurrent user at long context costs more, so leave headroom.
It works. Compare $0.1083 per 1M tokens against the alternatives below — the cheapest option that fits the same workload is 4× RTX 3080 10GB at $0.0511, and the fastest is 1× Cerebras CS-3 (WSE-3) at 8423 tok/s.
Same formulas, your context length, concurrency, and quantisation.