Is unified memory on Mac Studio M2 Ultra 128GB as fast as VRAM for starcoder2 15b i1?

Not always. Mac Studio M2 Ultra 128GB 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.

Can starcoder2 15b i1 run on Mac Studio M2 Ultra 128GB?

YES — Runs Great

C46Usable

Estimated from fit model

starcoder2 15b i1 needs ~25.6 GB VRAM. Mac Studio M2 Ultra 128GB has 92.2 GB. With Q4_K_M quantization, expect ~51 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

Q4_K_M (Medium quality) — 25.6 GB, 50.7 tok/s, Runs well

25.6 GB required92.2 GB available

28% VRAM used

Fit status

Runs well

Decode

50.7 tok/s

TTFT

3818 ms

Safe context

622K

Memory

25.6 GB / 92.2 GB

Memory breakdown

Weights9.2 GB

KV Cache1.8 GB

Runtime0.9 GB

Headroom13.8 GB

See how fast it feels

See how fast it feelsstarcoder2 15b i1 on Mac Studio M2 Ultra 128GB
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: 50.7 tok/s decode · 3.8s TTFT (warm) · 127 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	50.7 tok/s	2082 ms	622K
Coding	C	Runs well	50.7 tok/s	3818 ms	622K
Agentic Coding	C	Runs well	50.7 tok/s	5553 ms	622K
Reasoning	C	Runs well	50.7 tok/s	4512 ms	622K
RAG	C	Runs well	50.7 tok/s	6941 ms	622K

Quantization options

How starcoder2 15b i1 (15B params) fits at each quantization level on Mac Studio M2 Ultra 128GB (92.2 GB usable).

Quant	Bits	VRAM	Quality	Fit
Q2_K	2	5.9 GB	Low	D39
Q3_K_S	3	7.4 GB	Low	D39
NVFP4	4

Get started

Copy-paste commands to run starcoder2 15b i1 on your machine.

Run

lms load hf-mradermacher--starcoder2-15b-i1-gguf && lms server start

Upgrade options

Hardware that runs starcoder2 15b i1 well

RTX PRO 6000 Blackwell Workstation Edition 96GBBudget pick

1792 GB/s (+992)

Raises estimated decode speed by about 224%.164.5 tok/s decode

Raises estimated decode speed by about 224%.

~$9,999 MSRP

RTX PRO 6000 Blackwell Server Edition 96GBBest value

1597 GB/s (+797)

Raises estimated decode speed by about 189%.146.6 tok/s decode

Raises estimated decode speed by about 189%.

~$9,999 MSRP

Frequently asked questions

Can Mac Studio M2 Ultra 128GB run starcoder2 15b i1?

Yes, Mac Studio M2 Ultra 128GB can run starcoder2 15b i1 with a C grade (Runs well). Expected decode speed: 50.7 tok/s.

How much VRAM does starcoder2 15b i1 need?

starcoder2 15b i1 (15B parameters) requires approximately 25.6 GB of memory with Q4_K_M quantization.

What is the best quantization for starcoder2 15b i1?

The recommended quantization for starcoder2 15b i1 is Q4_K_M, which balances quality and memory efficiency.

What speed will starcoder2 15b i1 run at on Mac Studio M2 Ultra 128GB?

On Mac Studio M2 Ultra 128GB, starcoder2 15b i1 achieves approximately 50.7 tokens per second decode speed with a time-to-first-token of 3818ms using Q4_K_M quantization.

Can Mac Studio M2 Ultra 128GB run starcoder2 15b i1 for coding?

For coding workloads, starcoder2 15b i1 on Mac Studio M2 Ultra 128GB receives a C grade with 50.7 tok/s and 622K context.

What context window can starcoder2 15b i1 use on Mac Studio M2 Ultra 128GB?

On Mac Studio M2 Ultra 128GB, starcoder2 15b i1 can safely use up to 622K tokens of context. The model's official context limit is —, but available memory constrains the safe maximum.

See all results for Mac Studio M2 Ultra 128GB See all hardware for starcoder2 15b i1

Embed this result▼

Paste this snippet into any page to show a live fit card.

<iframe src="https://willitrunai.com/embed/hf-mradermacher--starcoder2-15b-i1-gguf-on-m2-ultra-128gb" width="400" height="180" frameborder="0" style="border:none;border-radius:12px;overflow:hidden;" title="Will It Run AI — fit result"></iframe>

Preview: