HARDWARE FIT CHECK • Qwen 2.5 72B Instruct + NVIDIA DGX Spark (128GB Grace-Blackwell Unified)51.27 GB / 118 GB VRAM

Can I Run Qwen 2.5 72B Instruct on NVIDIA DGX Spark (128GB Grace-Blackwell Unified)?

Full VRAM footprint analysis, tokens/sec generation benchmark, and copy-paste Ollama & vLLM runtime commands for running Qwen 2.5 72B Instruct (72.7B) on NVIDIA DGX Spark (128GB Grace-Blackwell Unified) (118 GB).

✓ FITS IN VRAM51.27 GB (43%)~4 t/s

Target Hardware & Model

interactive
Top general benchmark open weights model for dual RTX 3090 (48GB) setups
Qwen 2.5 72B Instruct on NVIDIA DGX Spark (128GB Grace-Blackwell Unified)

✓ Fits Comfortably in VRAM

✓ FITS IN VRAM
Required VRAM
51.27 GB
43% of hardware capacity (118 GB)
Est. Decode Speed
~4 tok/s
Dense model @ 273 GB/s
Available Headroom
+66.73 GB
Safe for OS display & full context
Memory Allocation & Headroom
51.27 GB allocated of 118 GB capacity
43% utilized
Weights: 43.62 GB
KV: (32K): 5.37 GB
Overhead: 2.28 GB
Free Headroom: +66.73 GB
⚡ Architecture & Throughput Transparency: Single-user decode speed (~4 tok/s) is memory-bandwidth bound at batch size = 1 on NVIDIA DGX Spark (128GB Grace-Blackwell Unified) (273 GB/s). Prompt prefill / TTFT (~58 tok/s) is compute-bound and utilizes GPU Tensor cores. Actual latency varies with FlashAttention-2 and runtime engine (Ollama/vLLM/llama.cpp).

Local Hardware Configurations & Pricing

High-bandwidth VRAM specs and current market prices
Multi-GPU Rig
48 GB VRAM

2x NVIDIA RTX 3090 Dual Rig (48GB Total VRAM)

Best price-to-VRAM homelab rig for 70B Q4_K_M & Qwen 3.8 27B Q8

936 GB/s700W TDP
Apple Silicon
112 GB VRAM

Apple Mac Studio M4 Max (128GB Unified Memory)

Running Llama 4 Scout 109B & 70B Q8 locally with 128K+ context

546 GB/s145W TDP
AI Appliance
118 GB VRAM

NVIDIA DGX Spark (128GB Grace-Blackwell Unified)

128GB Unified Memory with native CUDA + Blackwell FP4 support

273 GB/s170W TDP

Quantization Precision Matrix

32K ctx • KV: Q8_0
QuantizationWeightsKV CacheTotal VRAMEst. SpeedFit Status
FP1616 bpw145.4 GB5.37 GB156.61 GB (133%)~1 t/sPARTIAL
Q8_08.5 bpw77.06 GB5.37 GB85.88 GB (73%)~2 t/sFITS
Q6_K6.56 bpw59.61 GB5.37 GB67.82 GB (57%)~3 t/sFITS
Q5_K_M5.68 bpw51.62 GB5.37 GB59.55 GB (50%)~3 t/sFITS
Q4_K_M4.8 bpw43.62 GB5.37 GB51.27 GB (43%)~4 t/sFITS
FP44.25 bpw38.53 GB5.37 GB46 GB (39%)~5 t/sFITS
IQ3_XS3.3 bpw29.81 GB5.37 GB36.97 GB (31%)~6 t/sFITS

Export Full Architecture & Infrastructure Spec

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FAQ & Reference

Frequently Asked Questions: Qwen 2.5 72B Instruct on NVIDIA DGX Spark (128GB Grace-Blackwell Unified)

How much VRAM does Qwen 2.5 72B Instruct need on NVIDIA DGX Spark (128GB Grace-Blackwell Unified)?

At standard 4-bit quantization (Q4_K_M) with 32K context, Qwen 2.5 72B Instruct requires 51.27 GB of total VRAM (weights + KV cache + CUDA runtime overhead).

What inference speed will Qwen 2.5 72B Instruct achieve on NVIDIA DGX Spark (128GB Grace-Blackwell Unified)?

Based on NVIDIA DGX Spark (128GB Grace-Blackwell Unified)'s 273 GB/s memory bandwidth, expected decode speed is approximately 4 tokens per second.

Can I expand context beyond 32K tokens?

Each additional 32K tokens of context requires additional KV cache memory. For longer context windows, consider 8-bit or 4-bit KV cache quantization.