Qwen3.5 122B-A10B on MTT S4000 48GB (摩尔线程) (48GB) — VRAM, KV Cache & Throughput
Qwen3.5 122B-A10B (122B total, 10B active, Hybrid Linear/Mamba + MoE) uses 69.19 GiB of 4-bit weights (Q4_K_M), requiring 70.03 GiB total at 8K context and 70.59 GiB at 32K on MTT S4000 48GB (摩尔线程) (~19.5 tok/s decode).
Recommended Hardware for Current Configuration
Production Launch Commands
llama-server -hf unsloth/Qwen3.5-122B-A10B-GGUF:Q4_K_M \ --ctx-size 8192 -ngl 999 --flash-attn
vllm serve Qwen/Qwen3.5-122B-A10B \ --max-model-len 8192 --gpu-memory-utilization 0.92
Cloud GPU Comparison & Rent-vs-Buy TCO
Verified public rates across RunPod, Vast.ai, Vultr, and DigitalOcean.
| Provider | Recommended Instance | Total VRAM | Hourly Rate | Monthly at Selected Hours | Billing Mode | Deploy |
|---|---|---|---|---|---|---|
| RunPod | 1x A100 80GB SXM (Community Cloud · PCIe) | 80 GB | $1.19 / hr | $144.70 / mo | Per-second | Deploy GPU ↗ |
| Vast.ai | 1x A100 80GB SXM (Verified Host · SXM4) | 80 GB | $0.44 / hr | $53.75 / mo | Spot / On-demand | Deploy GPU ↗ |
| Vultr ($300 Free Credit*) | 1x A100 80GB SXM (Dedicated Instance · $300 Credit*) | 80 GB | $2.40 / hr | $291.48 / mo | Hourly | Deploy GPU ↗ |
| Vultr Cloud GPU | 1x A100 80GB SXM (Dedicated Instance) | 80 GB | $2.40 / hr | $291.48 / mo | Hourly | Deploy GPU ↗ |
| DigitalOcean | 1x Instinct MI300X 192GB (Dedicated Instance) | 192 GB | $2.59 / hr | $314.94 / mo | Per-second | Deploy GPU ↗ |
Rates reflect public listings on the verification date and fluctuate with regional inventory.
Fine-Tuning VRAM Requirements (QLoRA / LoRA / Full) — Qwen3.5 122B-A10B
Engineering Sizing Notes & Optimization Playbook
Quick Hardware Verdict
A single MTT S4000 48GB (摩尔线程) (48GB) cannot hold 4-bit Qwen3.5 122B-A10B (70.03 GiB at 8K) entirely in VRAM. Use multi-GPU tensor parallelism, offload layers to system RAM, or deploy on a larger cloud GPU.
KV Cache & Runtime Tuning
Qwen3.5 122B-A10B uses Hybrid Linear/Mamba + MoE (122B total, 10B active per token). Moving from 8K to 32K context expands FP16 KV cache from 0.28 GiB to 0.84 GiB; enabling 8-bit KV cache (llama.cpp -ctk q8_0 -ctv q8_0 or vLLM --kv-cache-dtype fp8) saves 0.38 GiB at 32K (reducing total VRAM to 70.21 GiB).
VRAM Scaling Across Context Windows (4K to 128K, 4-bit Weights)
Quantization Precision & Memory Matrix — Qwen3.5 122B-A10B @ 8K
| Quantization Format | Weights (GiB) | KV Cache | Total VRAM (GiB) | Decode Speed | Compatibility (MTT S4000 48GB (摩尔线程)) | Recommended GPU | Data Source |
|---|---|---|---|---|---|---|---|
| Native Weights (BF16 / FP8 / MXFP4 — Lossless) (BF16) | 227.24 GiB | 0.28 GiB | 228.08 GiB (244.9 GB) | ~3.3 tok/s | Exceeds Available GPU Memory | Instinct MI325X 256GB (256GB) | Official checkpoint size |
| FP8 / GGUF Q8_0 (8-bit — Near-Lossless) (Q8_0) | 120.72 GiB | 0.28 GiB | 121.56 GiB (130.52 GB) | ~7.4 tok/s | Exceeds Available GPU Memory | Instinct MI300X 192GB (192GB) | Config-derived formula |
| GGUF Q6_K (6-bit — High Precision) (Q6_K) | 93.17 GiB | 0.28 GiB | 94.01 GiB (100.94 GB) | ~11 tok/s | Exceeds Available GPU Memory | Instinct MI300X 192GB (192GB) | Config-derived formula |
| GGUF Q5_K_M (5-bit — Balanced) (Q5_K_M) | 80.97 GiB | 0.28 GiB | 81.81 GiB (87.84 GB) | ~14.1 tok/s | Exceeds Available GPU Memory | RTX PRO 6000 Blackwell (96GB) | Config-derived formula |
| Q4_K_M / UD-Q4_K_XL / AWQ (4-bit — Recommended) (Q4_K_M) | 69.19 GiB | 0.28 GiB | 70.03 GiB (75.19 GB) | ~19.5 tok/s | Exceeds Available GPU Memory | RTX PRO 6000 Blackwell (96GB) | Config-derived formula |
| GGUF IQ4_XS (4.25-bit — Compact) (IQ4_XS) | 60.58 GiB | 0.28 GiB | 61.42 GiB (65.95 GB) | ~27.3 tok/s | Exceeds Available GPU Memory | RTX PRO 6000 Blackwell (96GB) | Config-derived formula |
| GGUF Q3_K_M (3-bit — Low VRAM) (Q3_K_M) | 55.73 GiB | 0.28 GiB | 56.57 GiB (60.74 GB) | ~35.6 tok/s | Exceeds Available GPU Memory | RTX PRO 6000 Blackwell (96GB) | Config-derived formula |
| GGUF UD-Q2_K_XL (2-bit — Extreme MoE) (UD-Q2_K_XL) | 39.37 GiB | 0.28 GiB | 40.21 GiB (43.18 GB) | ~90.3 tok/s | Fits with Safe Headroom | A40 48GB (48GB) | Config-derived formula |
Technical Specifications & FAQ
Does Qwen3.5 122B-A10B fit on MTT S4000 48GB (摩尔线程) (48GB)?
In 4-bit (Q4_K_M) at 8,192 context, Qwen3.5 122B-A10B requires 70.03 GiB total GPU memory (69.19 GiB weights + 0.28 GiB KV cache + 0.56 GiB runtime buffers) against 45.6 GiB usable on MTT S4000 48GB (摩尔线程), delivering ~19.5 tok/s decode.
How much VRAM does Qwen3.5 122B-A10B need at 32K context?
At 32,768 context tokens, Qwen3.5 122B-A10B (Hybrid Linear/Mamba + MoE) allocates 0.84 GiB for KV cache and state, bringing total 4-bit VRAM to 70.59 GiB (75.8 GB decimal).