Can Qwen 3.5 27B run on Radeon RX 6850M XT 12GB?

Q: What should I upgrade first if Qwen 3.5 27B feels slow on Radeon RX 6850M XT 12GB?

Add more VRAM headroom. The first useful upgrade is more dedicated VRAM so you can fit the model without shrinking context or dropping to a much lower quant.

NO — Won't Fit

F0Won't run

Estimated from fit model

Qwen 3.5 27B needs ~21.7 GB but Radeon RX 6850M XT 12GB only has 12.0 GB. Try a smaller quantization or lighter model.

Runtime: llama.cppCapacity: No fitBandwidth: LowStack: 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

Q4_K_M (Medium quality) — 21.7 GB, exceeds 12.0 GB available

21.7 GB required12.0 GB available

181% VRAM needed

9.7 GB over capacity — needs offload or smaller quantization

Fit status

Too heavy

Decode

3.4 tok/s

TTFT

56867 ms

Safe context

Memory

21.7 GB / 12.0 GB

Offload

40%

Memory breakdown

Weights16.5 GB

KV Cache3.2 GB

Runtime0.9 GB

Headroom1.2 GB

See how fast it feels

With memory offload — actual speed may be lower

See how fast it feelsQwen 3.5 27B on Radeon RX 6850M XT 12GB
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: 3.4 tok/s decode · 56.9s TTFT (warm) · 9 tok/s prefill

What limits this setup

Usable VRAM is the main blocker for this model.

Not enough usable memory

The model needs 21.7 GB, but this setup only exposes 12.0 GB of usable VRAM.

Best improvement path

Add more VRAM headroom

The first useful upgrade is more dedicated VRAM so you can fit the model without shrinking context or dropping to a much lower quant.

Performance by workload

Workload	Grade	Fit	Decode	TTFT	Context
Chat	F	Too heavy	4.0 tok/s	26445 ms	4K
Coding	F	Too heavy	3.4 tok/s	56867 ms	4K
Agentic Coding	F	Too heavy	2.6 tok/s	110190 ms	4K
Reasoning	F	Too heavy	3.4 tok/s	67206 ms	4K
RAG	F	Too heavy	2.6 tok/s	137737 ms	4K

Quantization options

How Qwen 3.5 27B (27B params) fits at each quantization level on Radeon RX 6850M XT 12GB (12.0 GB usable).

Quant	Bits	VRAM	Quality	Fit
Q2_K	2	10.5 GB	Low	F0
Q3_K_S	3	13.2 GB	Low	F0
NVFP4	4

Upgrade options

Hardware that runs Qwen 3.5 27B well

RX 7900 XT 20GBBest value

20 GB VRAM (+8)800 GB/s (+368)

Makes the model fit on the accelerator instead of staying completely out of reach.18.3 tok/s decode

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

Raises estimated decode speed by about 438%.

~$899 MSRP

RX 7900 XTX 24GBBudget pick

24 GB VRAM (+12)960 GB/s (+528)

Makes the model fit on the accelerator instead of staying completely out of reach.45.3 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.

~$999 MSRP

Radeon AI PRO R9700 32GBAMD upgrade

32 GB VRAM (+20)640 GB/s (+208)

Makes the model fit on the accelerator instead of staying completely out of reach.24.8 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.

~$1,899 MSRP

Frequently asked questions

Can Radeon RX 6850M XT 12GB run Qwen 3.5 27B?

No, Qwen 3.5 27B requires more memory than Radeon RX 6850M XT 12GB provides.

How much VRAM does Qwen 3.5 27B need?

Qwen 3.5 27B (27B parameters) requires approximately 21.7 GB of memory with Q4_K_M quantization.

What is the best quantization for Qwen 3.5 27B?

The recommended quantization for Qwen 3.5 27B is Q4_K_M, which balances quality and memory efficiency.

What speed will Qwen 3.5 27B run at on Radeon RX 6850M XT 12GB?

On Radeon RX 6850M XT 12GB, Qwen 3.5 27B achieves approximately 3.4 tokens per second decode speed with a time-to-first-token of 56867ms using Q4_K_M quantization.

Can Radeon RX 6850M XT 12GB run Qwen 3.5 27B for coding?

For coding workloads, Qwen 3.5 27B on Radeon RX 6850M XT 12GB receives a F grade with 3.4 tok/s and 4K context.

What context window can Qwen 3.5 27B use on Radeon RX 6850M XT 12GB?

On Radeon RX 6850M XT 12GB, Qwen 3.5 27B can safely use up to 4K tokens of context. The model's official context limit is 131K, but available memory constrains the safe maximum.

What should I upgrade first if Qwen 3.5 27B feels slow on Radeon RX 6850M XT 12GB?

See all results for Radeon RX 6850M XT 12GB See all hardware for Qwen 3.5 27B

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