Is unified memory on Mac Studio M2 Ultra 128GB as fast as VRAM for DeepSeek V4 Flash?

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 DeepSeek V4 Flash run on Mac Studio M2 Ultra 128GB?

Q: What should I upgrade first if DeepSeek V4 Flash feels slow on Mac Studio M2 Ultra 128GB?

Move to a larger memory pool. A larger unified-memory SKU or a discrete high-bandwidth GPU is the cleanest way to make this model practical.

NO — Won't Fit

F0Won't run

Estimated from fit model

DeepSeek V4 Flash needs ~175.1 GB but Mac Studio M2 Ultra 128GB only has 92.2 GB. Try a smaller quantization or lighter model.

Runtime: llama.cppCapacity: No fitBandwidth: HighStack: StandardBottleneck: Memory capacity

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

NVFP4 (Medium quality) — 174.0 GB, exceeds 92.2 GB available

174.0 GB required92.2 GB available

189% VRAM needed

81.8 GB over capacity — needs offload or smaller quantization

Fit status

Too heavy

Decode

7.0 tok/s

TTFT

27585 ms

Safe context

Memory

174.0 GB / 92.2 GB

Offload

50%

Memory breakdown

Weights158.0 GB

KV Cache1.3 GB

Runtime0.9 GB

Headroom13.8 GB

See how fast it feels

With memory offload — actual speed may be lower

See how fast it feelsDeepSeek V4 Flash 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: 7.0 tok/s decode · 27.6s TTFT (warm) · 18 tok/s prefill

What limits this setup

Usable shared or unified memory is the main blocker for this model.

Not enough usable memory

The model needs 175.1 GB, but this setup only exposes 92.2 GB of usable shared or unified memory.

Best improvement path

Move to a larger memory pool

A larger unified-memory SKU or a discrete high-bandwidth GPU is the cleanest way to make this model practical.

Performance by workload

Workload	Grade	Fit	Decode	TTFT	Context
Chat	F	Too heavy	7.0 tok/s	14985 ms	4K
Coding	F	Too heavy	6.3 tok/s	30497 ms	4K
Agentic Coding	F	Too heavy	7.0 tok/s	40388 ms	4K
Reasoning	F	Too heavy	7.0 tok/s	32600 ms	4K
RAG	F	Too heavy	7.0 tok/s	50485 ms	4K

Quantization options

How DeepSeek V4 Flash (284B params) fits at each quantization level on Mac Studio M2 Ultra 128GB (92.2 GB usable).

Quant	Bits	VRAM	Quality	Fit
Q2_K	2	110.8 GB	Low	F0
Q3_K_S	3	139.2 GB	Low	F0
NVFP4	4

Upgrade options

Hardware that runs DeepSeek V4 Flash well

Mac Studio M3 Ultra 256GBBudget pick

256 GB Unified (+128)819 GB/s (+19)

Makes the model fit on the accelerator instead of staying completely out of reach.17.8 tok/s decode

Makes the model fit on the accelerator instead of staying completely out of reach.

Removes host-memory offload, which is usually the single biggest latency and throughput win.

~$6,999 MSRP

AMD Instinct MI350X 288GBBest value

288 GB VRAM (+160)8000 GB/s (+7200)

Makes the model fit on the accelerator instead of staying completely out of reach.125.8 tok/s decode

Makes the model fit on the accelerator instead of staying completely out of reach.

Removes host-memory offload, which is usually the single biggest latency and throughput win.

~$8,000 MSRP

Frequently asked questions

Can Mac Studio M2 Ultra 128GB run DeepSeek V4 Flash?

No, DeepSeek V4 Flash requires more memory than Mac Studio M2 Ultra 128GB provides.

How much VRAM does DeepSeek V4 Flash need?

DeepSeek V4 Flash (284B parameters) requires approximately 175.1 GB of memory with NVFP4 quantization.

What is the best quantization for DeepSeek V4 Flash?

The recommended quantization for DeepSeek V4 Flash is NVFP4, which balances quality and memory efficiency.

What speed will DeepSeek V4 Flash run at on Mac Studio M2 Ultra 128GB?

On Mac Studio M2 Ultra 128GB, DeepSeek V4 Flash achieves approximately 6.3 tokens per second decode speed with a time-to-first-token of 30497ms using NVFP4 quantization.

Can Mac Studio M2 Ultra 128GB run DeepSeek V4 Flash for coding?

For coding workloads, DeepSeek V4 Flash on Mac Studio M2 Ultra 128GB receives a F grade with 6.3 tok/s and 4K context.

What context window can DeepSeek V4 Flash use on Mac Studio M2 Ultra 128GB?

On Mac Studio M2 Ultra 128GB, DeepSeek V4 Flash can safely use up to 4K tokens of context. The model's official context limit is 1.0M, but available memory constrains the safe maximum.

What should I upgrade first if DeepSeek V4 Flash feels slow on Mac Studio M2 Ultra 128GB?

See all results for Mac Studio M2 Ultra 128GB See all hardware for DeepSeek V4 Flash

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