| Model & Quantization | VRAM Demand | Apple Mac Studio M5 Max | Dual NVIDIA RTX 3090 |
|---|---|---|---|
| Meta LLaMA 3.3 70B (Q4_K_M, 8k) | 46.1 GB | Runs Comfortably (~16 tok/s) | Tight Fit (+1.9GB, ~18–26 tok/s) |
| Meta LLaMA 3.3 70B (Q5_K_M, 8k) | 54.9 GB | Fits w/ sysctl (56GB Limit) | Exceeds 48GB VRAM (-6.9GB) |
| Qwen 2.5 72B (Q4_K_M, 8k) | 47.3 GB | Fits w/ sysctl (+8.7GB) | Tight Fit (+0.7GB) |
| Alibaba Qwen3-Coder 30B-A3B (Q4_K_M) | 20.7 GB | Runs Comfortably (~135 tok/s MLX) | Runs Comfortably (~145 tok/s) |
| Qwen 2.5 Coder 32B (Q6_K, 8k) | 31.6 GB | Runs Comfortably (+16.4GB) | Runs Comfortably (+16.4GB) |
Apple's M5 Max expands unified memory across a 512-bit fabric hitting 614 GB/s alongside integrated Neural Accelerators inside each GPU cluster, letting `mlx-lm` stream dense 70B Q4_K_M weights at ~16 tok/s while keeping a compact ~80W–110W thermal footprint. Crucially, raising macOS wired allocation to 56 GB clears the 48GB ceiling where Dual RTX 3090 rigs stop, fitting both `70B Q5_K_M` (`54.88 GB`) and `70B Q4_K_M` with 32k FP8 KV-cache (`49.60 GB`). On the PC side, two Ampere GA102 cards aggregate 48GB across two 384-bit buses (1,872 GB/s combined) and retain physical 112.5 GB/s NVLink bridge support for vLLM `--tensor-parallel-size 2` all-reduce collectives. Dual 3090 rigs digest huge RAG documents 3x faster and execute CUDA diffusion natively, provided your motherboard and 1200W PSU handle 700W sustained heat.
On a 64GB Mac Studio M5 Max, run `sudo sysctl iogpu.wired_limit_mb=57344` so Darwin opens 56 GB of Metal memory for `70B Q5_K_M` (`54.88 GB`) without swapping. On Dual RTX 3090s, cap power via `nvidia-smi -pl 275` and pass `-fa on -ctk q8_0 -ctv q8_0` to shave ~150W of waste heat.
Matched Upgrade: Save over $1,200 on Apple's internal storage tiers by pairing a 64GB Mac Studio M5 Max with an OWC Express 1M2 40Gbps USB4 NVMe enclosure, loading massive 70B Q5_K_M and MLX libraries at 3,150+ MB/s externally.
OWC 40Gbps USB4 NVMe on Amazon Prime ↗Zero monthly subscriptions, 100% private inference, and unmetered tokens for your homelab or workstation.
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Mac Studio M5 Max idles near 10W and peaks around 80W–110W silently on a desk. Dual RTX 3090 workstations idle at 40W+ GPU-only and push 600W–750W total wall draw under load, demanding serious case airflow.
At 8k context, `70B Q5_K_M` needs 54.88 GB and `70B Q4_K_M` at 32k FP8 KV requires 49.60 GB—both exceed 48GB GDDR6X slightly unless you drop to Q4_0 KV-cache (`-ctk q4_0`) or step up to 64GB.
Inspect exact KV-cache formulas, test 32k/128k context allocations, or compare cloud rental break-even costs in the interactive matchmaker.
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