Can Phi 4 reasoning vision 15B run on RX 6600 XT 8GB?

Q: What should I upgrade first if Phi 4 reasoning vision 15B feels slow on RX 6600 XT 8GB?

Remove offload with more accelerator memory. Prioritize a GPU or unified-memory tier that fits the whole model natively. Removing offload usually helps more than small compute gains.

YES — With Q2_K

D37Poor

Estimated from fit model

Phi 4 reasoning vision 15B needs ~9.3 GB VRAM. RX 6600 XT 8GB has 8.0 GB. With Q2_K quantization, expect ~10 tok/s.

Runtime: llama.cppCapacity: OffloadBandwidth: LowStack: StandardBottleneck: Host offload

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.

Phi 4 reasoning vision 15B at Q4_K_M needs 12.6 GB — too much for RX 6600 XT 8GB (8.0 GB). Runs at Q2_K (9.3 GB) with low quality.

Capabilities:

Select quantization to explore

Q4_K_M (Medium quality) — 12.6 GB, exceeds 8.0 GB available

12.6 GB required8.0 GB available

158% VRAM needed

4.6 GB over capacity — needs offload or smaller quantization

Fit status

Too heavy

Decode

4.0 tok/s

TTFT

48073 ms

Safe context

Memory

12.6 GB / 8.0 GB

Offload

40%

Memory breakdown

Weights9.2 GB

KV Cache1.8 GB

Runtime0.9 GB

Headroom0.8 GB

See how fast it feels

With memory offload — actual speed may be lower

See how fast it feelsPhi 4 reasoning vision 15B on RX 6600 XT 8GB
1st promptCold start — includes initialization
>Solve: If a train travels at 60 mph for 2.5 hours, how far does it go?
Let me work through this step by step.

Given information:
  - Speed = 60 mph (miles per hour)
  - Time  = 2.5 hours

Formula: Distance = Speed x Time

Calculation:
  Distance = 60 mph x 2.5 h
           = 150 miles

The train travels 150 miles.

Double-check: at 60 mph the train covers 60 miles each hour. In half an hour it covers 30 miles. So in 2.5 hours: 60 + 60 + 30 = 150 miles. Confirmed.
2nd promptWarm — model ready, no init overhead
>What if the train stops for 20 minutes halfway?
The stop doesn't change the total distance covered while moving, but it affects total trip time.

Breakdown:
  - First half: 1.25 hours at 60 mph = 75 miles
  - Stop: 20 minutes (no distance)
  - Second half: 1.25 hours at 60 mph = 75 miles

Total distance: 150 miles (same)
Total time: 2.5 h + 0.33 h = 2.83 hours
Average speed: 150 / 2.83 = 53 mph

The distance stays the same but average speed drops to 53 mph because of the stop.
Estimated: 4.0 tok/s decode · 48.1s TTFT (warm) · 10 tok/s prefill

What limits this setup

It fits through host-memory offload, and offload is the main reason performance drops.

CPU or host-memory offload is active

About 10% of the working set spills out of accelerator memory, which usually hurts latency and sustained decode throughput.

Very little memory headroom

You can run the model, but there is not much room left for longer context, bigger batches, extra apps, or future model updates.

Best improvement path

Remove offload with more accelerator memory

Prioritize a GPU or unified-memory tier that fits the whole model natively. Removing offload usually helps more than small compute gains.

Buy headroom, not only minimum fit

A slightly larger memory tier gives you safer context growth and makes the recommendation more future-proof.

Increase host RAM if you keep offloading

This setup may need roughly 0.8 GB of extra host RAM just for the offloaded portion, before OS and other tools.

Performance by workload

Workload	Grade	Fit	Decode	TTFT	Context
Chat	F	Too heavy	4.7 tok/s	22521 ms	4K
Coding	F	Too heavy	4.0 tok/s	48073 ms	4K
Agentic Coding	F	Too heavy	3.1 tok/s	92034 ms	4K
Reasoning	F	Too heavy	4.0 tok/s	56813 ms	4K
RAG	F	Too heavy	3.1 tok/s	115042 ms	4K

Quantization options

How Phi 4 reasoning vision 15B (15B params) fits at each quantization level on RX 6600 XT 8GB (8.0 GB usable).

Quant	Bits	VRAM	Quality	Fit
Q2_K	2	5.9 GB	Low	F0
Q3_K_S	3	7.4 GB	Low	F0
NVFP4	4

Get started

Copy-paste commands to run Phi 4 reasoning vision 15B on your machine.

Run

lms load hf-jamesburton--phi-4-reasoning-vision-15b-gguf && lms server start

Upgrade options

Hardware that runs Phi 4 reasoning vision 15B well

RX 7600 XT 16GBBudget pick

16 GB VRAM (+8)288 GB/s (+32)

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.

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

~$329 MSRP

RX 9060 XT 16GBBest value

16 GB VRAM (+8)320 GB/s (+64)

Makes the model fit on the accelerator instead of staying completely out of reach.22 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.

~$349 MSRP

RX 7700 XT 12GBAMD upgrade

12 GB VRAM (+4)432 GB/s (+176)

Makes the model fit on the accelerator instead of staying completely out of reach.17.9 tok/s decode

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

Raises estimated decode speed by about 347%.

~$449 MSRP

RTX A4500 20GBBiggest leap

20 GB VRAM (+12)640 GB/s (+384)

Makes the model fit on the accelerator instead of staying completely out of reach.54.6 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.

~$2,000 MSRP

Frequently asked questions

Can RX 6600 XT 8GB run Phi 4 reasoning vision 15B?

Yes, RX 6600 XT 8GB can run Phi 4 reasoning vision 15B at Q2_K quantization (Very compromised (needs ~0.8 GB host RAM)). The recommended Q4_K_M requires 12.6 GB which exceeds available memory, but at Q2_K it needs only 9.3 GB. Expected decode speed: 10.1 tok/s.

How much VRAM does Phi 4 reasoning vision 15B need?

Phi 4 reasoning vision 15B (15B parameters) requires approximately 12.6 GB at Q4_K_M quantization. On RX 6600 XT 8GB, it fits at Q2_K using 9.3 GB.

What is the best quantization for Phi 4 reasoning vision 15B?

The recommended quantization is Q4_K_M, but on RX 6600 XT 8GB the best fitting quantization is Q2_K, which uses 9.3 GB.

What speed will Phi 4 reasoning vision 15B run at on RX 6600 XT 8GB?

On RX 6600 XT 8GB, Phi 4 reasoning vision 15B achieves approximately 10.1 tokens per second decode speed with a time-to-first-token of 19089ms using Q2_K quantization.

Can RX 6600 XT 8GB run Phi 4 reasoning vision 15B for coding?

For coding workloads, Phi 4 reasoning vision 15B on RX 6600 XT 8GB receives a F grade with 4.0 tok/s and 4K context.

What context window can Phi 4 reasoning vision 15B use on RX 6600 XT 8GB?

On RX 6600 XT 8GB, Phi 4 reasoning vision 15B can safely use up to 4K tokens of context at Q2_K quantization. The model's official context limit is —, but available memory constrains the safe maximum.

See all results for RX 6600 XT 8GB See all hardware for Phi 4 reasoning vision 15B

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