HARDWARE FIT CHECK • Meta Llama 3.1 8B Instruct + Apple Mac Studio M5 Ultra (256GB Unified Memory)7.87 GB / 236 GB VRAM

Can I Run Meta Llama 3.1 8B Instruct on Apple Mac Studio M5 Ultra (256GB Unified Memory)?

Full VRAM footprint analysis, tokens/sec generation benchmark, and copy-paste Ollama & vLLM runtime commands for running Meta Llama 3.1 8B Instruct (8B) on Apple Mac Studio M5 Ultra (256GB Unified Memory) (236 GB).

✅ Runs 100% in GPU VRAM (Optimal Headroom)7.87 GB (3%)~107 t/s

Model & Target Hardware

interactive
Fast 8GB–12GB GPU Chat, Classification & Local Agents
Meta Llama 3.1 8B Instruct on Apple Mac Studio M5 Ultra (256GB Unified Memory)

✓ Fits Comfortably in VRAM

✓ FITS IN VRAM
Required VRAM
7.87 GB
3% of hardware capacity (236 GB)
Est. Decode Speed
~107 tok/s
Dense model @ 890 GB/s
Available Headroom
+228.13 GB
Safe for OS display & full context
Memory Allocation & Headroom
7.87 GB allocated of 236 GB capacity
3% utilized
Weights: 4.8 GB
KV: (32K): 2.15 GB
Overhead: 0.92 GB
Free Headroom: +228.13 GB
⚡ Architecture & Throughput Transparency: Single-user decode speed (~107 tok/s) is memory-bandwidth bound at batch size = 1 on Apple Mac Studio M5 Ultra (256GB Unified Memory) (890 GB/s). Prompt prefill / TTFT (~1,552 tok/s) is compute-bound and utilizes GPU Tensor cores. Actual latency varies with FlashAttention-2 and runtime engine (Ollama/vLLM/llama.cpp).
OLLAMA_FLASH_ATTENTION=1 OLLAMA_KV_CACHE_TYPE=q8_0 ollama run llama3.1:8b

Quantization Precision Matrix

32K ctx • KV: Q8_0
QuantizationWeightsKV CacheTotal VRAMEst. SpeedFit Status
FP1616 bpw16 GB2.15 GB19.46 GB (8%)~34 t/sFITS
Q8_08.5 bpw8.48 GB2.15 GB11.68 GB (5%)~63 t/sFITS
Q6_K6.56 bpw6.56 GB2.15 GB9.69 GB (4%)~80 t/sFITS
Q5_K_M5.68 bpw5.68 GB2.15 GB8.78 GB (4%)~92 t/sFITS
Q4_K_M4.8 bpw4.8 GB2.15 GB7.87 GB (3%)~107 t/sFITS
FP44.25 bpw4.24 GB2.15 GB7.29 GB (3%)~119 t/sFITS
IQ3_XS3.3 bpw3.28 GB2.15 GB6.29 GB (3%)~149 t/sFITS

Local Hardware Configurations & Pricing

High-bandwidth VRAM specs and current market prices
Apple Silicon236 GB VRAM

Apple Mac Studio M5 Ultra (256GB Unified Memory)

Massive MoE models (DeepSeek V4.1 Q3/Q4) & 70B FP16 workstation

890 GB/s210W TDP
Consumer GPU32 GB VRAM

NVIDIA GeForce RTX 5090 (32GB GDDR7)

Maximum tokens/sec on 27B–35B models & Blackwell FP4 quantization

1792 GB/s575W TDP
Consumer GPU24 GB VRAM

NVIDIA GeForce RTX 4090 (24GB GDDR6X)

The 24GB CUDA enthusiast standard for 14B–32B Q4_K_M models

1008 GB/s450W TDP
Multi-GPU Rig48 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

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