Can the Mac mini M4 Pro 48GB run 32B models?

Yes, comfortably: ~36GB usable fits Qwen3 32B Q4 (~23.7GB) at a slow-but-readable ~10 tok/s; the same model is a tight fit on the 3090 but ~35 tok/s. The MoE Qwen3 30B-A3B runs ~101 tok/s on the Mac — a better experience overall.

Total cost: Mac mini vs a 3090 build?

The Mac mini's ~$1,799 is the whole machine; a used 3090 (~$1,100) still needs board/CPU/PSU/case, typically $1,500-1,800 total. Similar money, different form: silent appliance vs upgradeable custom build.

Which side can upgrade to run 70B?

Only the 3090: add a second card for 48GB layer-split 70B Q4. The Mac mini's memory is soldered — 70B Q4 (~47.4GB) will never fit in 36GB usable, so confirm your roadmap stops at the 32B tier.

GPU Comparisons / Mac mini M4 Pro (48GB) vs RTX 3090

Mac mini M4 Pro (48GB) vs RTX 3090 for Local LLMs: Which Should You Pick

Verdict

Silent, plug-and-play, targeting ≤32B: Mac mini. Want speed, the CUDA ecosystem, and an upgrade path (dual-card 70B): a used RTX 3090 build.

Spec Comparison

	Mac mini M4 Pro (48GB)	RTX 3090
Nominal VRAM	48 GB	24 GB
Usable VRAM (for models)	36.0 GB	24.0 GB
Memory bandwidth	273 GB/s	936 GB/s
Type	Unified memory	Discrete GPU
Release year	2024	2020
MSRP	$1,799	$1,499
Used reference price	—	$1,100
TDP	50 W	350 W

Apple unified memory is counted at 75% usable for models (the rest serves the system/display).

Model Verdict Matrix (Q4_K_M @8K)

Model	VRAM needed	Mac mini M4 Pro (48GB)	Theoretical speed	RTX 3090	Theoretical speed
Llama 3.2 3B	4.4 GB	Comfortable	≈104	Comfortable	≈357
Llama 3.1 8B	7.5 GB	Comfortable	≈42	Comfortable	≈143
Qwen3 8B	7.7 GB	Comfortable	≈41	Comfortable	≈140
Phi-4 14B	12.2 GB	Comfortable	≈23	Comfortable	≈78
Mistral Small 3.2 24B	17.5 GB	Comfortable	≈14	Comfortable	≈48
Gemma 3 27B	22.4 GB	Comfortable	≈12	Tight fit	≈42
Qwen3.8 27B	20.7 GB	Comfortable	≈12	Tight fit	≈41
Muse Glimmer 30B	20.1 GB	Comfortable	≈11	Tight fit	≈39
Qwen3 30B-A3B	21.0 GB	Comfortable	≈101	Tight fit	≈347
Qwen3 32B	23.7 GB	Comfortable	≈10	Tight fit	≈35
gpt-oss-20b	14.7 GB	Comfortable	≈93	Comfortable	≈318
Llama 3.3 70B	47.4 GB	Not feasible	—	Not feasible	—
gpt-oss-120b	73.6 GB	Not feasible	—	Not feasible	—
DeepSeek-R1 671B	413.1 GB	Not feasible	—	Not feasible	—

Highlighted rows = watershed models where the two cards' verdicts differ. Theoretical speed = bandwidth × 0.75 ÷ per-token weight bytes (active params for MoE); real-world results vary with framework/driver/CPU, ±30%. Speed is hidden for multi-GPU/infeasible verdicts.

Value Comparison

	Mac mini M4 Pro (48GB)	RTX 3090
Bandwidth per dollar	0.15 GB/s/$	0.85 GB/s/$
Usable VRAM per dollar	0.020 GB/$	0.022 GB/$

Pricing basis: Mac mini M4 Pro (48GB) = MSRP (no used price yet); RTX 3090 = used reference price; used prices are market estimates, see analysis for volatility.

Analysis

This comparison has a counterintuitive result: the Mac mini actually wins on capacity — 48GB unified memory yields ~36GB usable, making Gemma 3 27B, Qwen3.8 27B, Muse Glimmer 30B, Qwen3 30B-A3B and Qwen3 32B all comfortable, while the 24GB 3090 fits them only tight at the ceiling. But bandwidth is 273 vs 936 GB/s, a 3.4× gap: dense 32B Q4 theoretically ~10 vs ~35 tok/s, 8B ~42 vs ~143 tok/s. The Mac holds bigger models; the 3090 runs everything faster.

MoE is the Mac's remedy: Qwen3 30B-A3B activates only 3.3B params, hitting a theoretical ~101 tok/s on the Mac mini — the '36GB capacity + MoE models' combo feels far better than the bandwidth figure suggests. The form factor is a different world too: ~$1,799 new with warranty, ~50W whole-system, near-silent, plug-and-play; a used 3090 is ~$1,100 but needs a full build (board/CPU/850W PSU/cooling, typically $1,500-1,800 total), used-card inspection (GDDR6X temps, mining history), and draws 400W+.

The upgrade path is the fork: the 3090 can add a second card later — 48GB layer-split runs 70B Q4; the Mac mini's memory is soldered, and 70B Q4 (~47.4GB) will never fit in 36GB usable. Verdict: daily desktop use, noise/power-sensitive, model roadmap capped at the 32B tier (especially MoE) — the Mac mini is a zero-regret appliance; chasing the speed ceiling, the CUDA stack (vLLM, fine-tuning), or 70B on the roadmap — the used-3090 build is the only rational path.

FAQ

Can the Mac mini M4 Pro 48GB run 32B models?: Yes, comfortably: ~36GB usable fits Qwen3 32B Q4 (~23.7GB) at a slow-but-readable ~10 tok/s; the same model is a tight fit on the 3090 but ~35 tok/s. The MoE Qwen3 30B-A3B runs ~101 tok/s on the Mac — a better experience overall.
Total cost: Mac mini vs a 3090 build?: The Mac mini's ~$1,799 is the whole machine; a used 3090 (~$1,100) still needs board/CPU/PSU/case, typically $1,500-1,800 total. Similar money, different form: silent appliance vs upgradeable custom build.
Which side can upgrade to run 70B?: Only the 3090: add a second card for 48GB layer-split 70B Q4. The Mac mini's memory is soldered — 70B Q4 (~47.4GB) will never fit in 36GB usable, so confirm your roadmap stops at the 32B tier.

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Data verified 2026-09-01