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URL: https://willitrunai.com/can-run/internlm-20b-on-m2-ultra-64gb


Can InternLM 20B run on Mac Studio M2 Ultra 64GB?

YES — Tight Fit

B58Good
Estimated from fit model

InternLM 20B needs ~40.5 GB VRAM. Mac Studio M2 Ultra 64GB has 46.1 GB. With Q5_K_M quantization, expect ~33 tok/s.

Runtime: llama.cppCapacity: TightBandwidth: HighStack: StandardBottleneck: Balanced
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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) — 40.5 GB, 32.9 tok/s, Tight fit
40.5 GB required46.1 GB available
88% VRAM used

Fit status

Tight fit

Decode

32.9 tok/s

TTFT

5890 ms

Safe context

8K

Memory

40.5 GB / 46.1 GB

Memory breakdown

Weights14.4 GB
KV Cache18.3 GB
Runtime0.9 GB
Headroom6.9 GB

See how fast it feels

See how fast it feelsInternLM 20B on Mac Studio M2 Ultra 64GB
1st promptCold start — includes initialization
>Write a Python function to sort a list
Here's a Python function that sorts a list using quicksort: def quicksort(arr): if len(arr) <= 1: return arr pivot = arr[len(arr) // 2] left = [x for x in arr if x < pivot] middle = [x for x in arr if x == pivot] right = [x for x in arr if x > pivot] return quicksort(left) + middle + quicksort(right) # Example usage numbers = [3, 6, 8, 10, 1, 2, 1] print(quicksort(numbers)) # [1, 1, 2, 3, 6, 8, 10] The algorithm picks a pivot, partitions the list into smaller, equal, and larger elements, then recursively sorts each partition and concatenates the results.
2nd promptWarm — model ready, no init overhead
>Now add type hints and a docstring
def quicksort(arr: list[int]) -> list[int]: """Sort a list using the quicksort algorithm. Args: arr: List of integers to sort. Returns: A new sorted list. """ if len(arr) <= 1: return arr pivot = arr[len(arr) // 2] left = [x for x in arr if x < pivot] middle = [x for x in arr if x == pivot] right = [x for x in arr if x > pivot] return quicksort(left) + middle + quicksort(right) Added type hints for the input and return type, plus a Google-style docstring.
Estimated: 32.9 tok/s decode · 5.9s TTFT (warm) · 82 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

WorkloadGradeFitDecodeTTFTContext
ChatBRuns well32.9 tok/s3213 ms8K
CodingBTight fit32.9 tok/s5890 ms8K
Agentic CodingFToo heavy23.2 tok/s12141 ms8K
ReasoningBTight fit32.9 tok/s6961 ms8K
RAGFToo heavy23.2 tok/s15176 ms8K

Quantization options

How InternLM 20B (20B params) fits at each quantization level on Mac Studio M2 Ultra 64GB (46.1 GB usable).

QuantBitsVRAMQualityFit
Q2_K
2
7.8 GB
LowC50
Q3_K_S
3
9.8 GB
LowC51
NVFP4
4

Get started

Copy-paste commands to run InternLM 20B on your machine.

Run

docker run --rm -it ghcr.io/ggerganov/llama.cpp:full \ --hf-repo "internlm/internlm2_5-20b-chat" \ --hf-file "internlm2_5-20b-chat-Q5_K_M.gguf" \ -c 4096 -ngl 99

Upgrade options

Hardware that runs InternLM 20B well

MacBook Pro M4 Max 96GBBudget pick
96 GB Unified (+32)
B
Adds memory headroom for longer context windows and future model growth.30.7 tok/s decode

Adds memory headroom for longer context windows and future model growth.

~$2,499 MSRP

Mac Studio M3 Ultra 96GBBest value
96 GB Unified (+32)819 GB/s (+19)
B
Adds memory headroom for longer context windows and future model growth.39.4 tok/s decode

Adds memory headroom for longer context windows and future model growth.

~$3,999 MSRP

Frequently asked questions

See all results for Mac Studio M2 Ultra 64GBSee all hardware for InternLM 20B
11.2 GB
Medium
C51
Q4_K_M
4
12.2 GB
MediumC52
Q5_K_M
5
14.4 GB
HighC52
Q6_K
6
16.4 GB
HighC53
Q8_0Best for your GPU
8
21.4 GB
Very HighC55
F16
16
41.0 GB
MaximumF0

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.