Can StableLM 2 12B run on Mac Studio M2 Ultra 64GB?

Q: Is unified memory on Mac Studio M2 Ultra 64GB as fast as VRAM for StableLM 2 12B?

Not always. Mac Studio M2 Ultra 64GB can often fit larger models thanks to unified memory, but a discrete GPU with dedicated high-bandwidth VRAM may still decode faster once the model fits. For this combination, the important distinction is capacity versus sustained throughput.

YES — Runs Great

C53Usable

Estimated from fit model

StableLM 2 12B needs ~28.7 GB VRAM. Mac Studio M2 Ultra 64GB has 46.1 GB. With Q5_K_M quantization, expect ~50 tok/s.

Runtime: llama.cppCapacity: RoomyBandwidth: HighStack: StandardBottleneck: Balanced

Operating mode

Choose the run profile you care about

Interactive favors responsiveness, while light API and scale-out lean harder on serving readiness. The fit stays the same, but the recommendation lens changes.

Current mode

Balanced

Balanced for general local use. Keeps the ranking neutral across personal and serving workflows.

Capabilities:

Select quantization to explore

Q5_K_M (High quality) — 28.7 GB, 50.1 tok/s, Runs well

28.7 GB required46.1 GB available

62% VRAM used

Fit status

Runs well

Decode

50.1 tok/s

TTFT

3864 ms

Safe context

Memory

28.7 GB / 46.1 GB

Memory breakdown

Weights8.6 GB

KV Cache12.2 GB

Runtime0.9 GB

Headroom6.9 GB

See how fast it feels

See how fast it feelsStableLM 2 12B on Mac Studio M2 Ultra 64GB
1st promptCold start — includes initialization
>What is local AI inference?
Local AI inference means running an AI language model directly on your own hardware — your laptop, desktop, or server — instead of sending requests to a remote cloud API.

When you run inference locally the model weights are loaded into your GPU or unified memory. Each token you generate requires reading those weights from memory, so memory bandwidth is the main bottleneck for decode speed.

Key benefits of running locally:
  - Full privacy: your prompts never leave your machine
  - No per-token cost or rate limits
  - Works offline once the model is downloaded
  - Latency depends only on your hardware
2nd promptWarm — model ready, no init overhead
>How much VRAM do I need?
It depends on the model size and quantization level. A rough rule of thumb:

  Model size     Q4 (4-bit)    Q8 (8-bit)    FP16
  7B params      ~4.3 GB       ~7.5 GB       ~14 GB
  13B params     ~7.9 GB       ~13.9 GB      ~26 GB
  70B params     ~42.7 GB      ~74.9 GB      ~140 GB

Most people use 4-bit quantization (Q4_K_M) which gives 90-95% of full quality at a fraction of the memory. A 24 GB GPU can comfortably run most 7B-13B models.
Estimated: 50.1 tok/s decode · 3.9s TTFT (warm) · 125 tok/s prefill

What limits this setup

This setup is broadly balanced for this model.

Shared-memory contention still exists

The OS, browser, and inference runtime all compete for the same physical memory pool, so real-world headroom is less forgiving than raw capacity suggests.

Best improvement path

Performance by workload

Workload	Grade	Fit	Decode	TTFT	Context
Chat	C	Runs well	50.1 tok/s	2108 ms	4K
Coding	C	Runs well	50.1 tok/s	3864 ms	4K
Agentic Coding	C	Tight fit	50.1 tok/s	5621 ms	4K
Reasoning	C	Runs well	50.1 tok/s	4567 ms	4K
RAG	C	Tight fit	50.1 tok/s	7026 ms	4K

Quantization options

How StableLM 2 12B (12B params) fits at each quantization level on Mac Studio M2 Ultra 64GB (46.1 GB usable).

Quant	Bits	VRAM	Quality	Fit
Q2_K	2	4.7 GB	Low	C42
Q3_K_S	3	5.9 GB	Low	C42
NVFP4	4

Get started

Copy-paste commands to run StableLM 2 12B on your machine.

Run

docker run --rm -it ghcr.io/ggerganov/llama.cpp:full \
  --hf-repo "stabilityai/stablelm-2-12b-chat" \
  --hf-file "stablelm-2-12b-chat-Q5_K_M.gguf" \
  -c 4096 -ngl 99

Upgrade options

Hardware that runs StableLM 2 12B well

RTX PRO 5000 Blackwell 48GBBudget pick

1344 GB/s (+544)

Raises estimated decode speed by about 100%.100 tok/s decode

Raises estimated decode speed by about 100%.

~$4,999 MSRP

Frequently asked questions

Can Mac Studio M2 Ultra 64GB run StableLM 2 12B?

Yes, Mac Studio M2 Ultra 64GB can run StableLM 2 12B with a C grade (Runs well). Expected decode speed: 50.1 tok/s.

How much VRAM does StableLM 2 12B need?

StableLM 2 12B (12B parameters) requires approximately 28.7 GB of memory with Q5_K_M quantization.

What is the best quantization for StableLM 2 12B?

The recommended quantization for StableLM 2 12B is Q5_K_M, which balances quality and memory efficiency.

What speed will StableLM 2 12B run at on Mac Studio M2 Ultra 64GB?

On Mac Studio M2 Ultra 64GB, StableLM 2 12B achieves approximately 50.1 tokens per second decode speed with a time-to-first-token of 3864ms using Q5_K_M quantization.

Can Mac Studio M2 Ultra 64GB run StableLM 2 12B for coding?

For coding workloads, StableLM 2 12B on Mac Studio M2 Ultra 64GB receives a C grade with 50.1 tok/s and 4K context.

What context window can StableLM 2 12B use on Mac Studio M2 Ultra 64GB?

On Mac Studio M2 Ultra 64GB, StableLM 2 12B can safely use up to 4K tokens of context. The model's official context limit is 4K, but available memory constrains the safe maximum.

Is unified memory on Mac Studio M2 Ultra 64GB as fast as VRAM for StableLM 2 12B?

See all results for Mac Studio M2 Ultra 64GB See all hardware for StableLM 2 12B

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