Can Phi 3 Medium 14B run on RX 6900 XT 16GB?

YES — Tight Fit

B62Good

Estimated from fit model

Phi 3 Medium 14B needs ~14.1 GB VRAM. RX 6900 XT 16GB has 16.0 GB. With Q4_K_M quantization, expect ~34 tok/s.

Runtime: llama.cppCapacity: TightBandwidth: MediumStack: 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) — 14.1 GB, 36.7 tok/s, Tight fit

14.1 GB required16.0 GB available

88% VRAM used

Fit status

Tight fit

Decode

36.7 tok/s

TTFT

5270 ms

Safe context

26K

Memory

14.1 GB / 16.0 GB

Memory breakdown

Weights8.5 GB

KV Cache3.1 GB

Runtime0.9 GB

Headroom1.6 GB

See how fast it feels

See how fast it feelsPhi 3 Medium 14B on RX 6900 XT 16GB
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: 36.7 tok/s decode · 5.3s TTFT (warm) · 92 tok/s prefill

What limits this setup

This setup is broadly balanced for this model.

No major red flags

This recommendation has enough memory headroom and acceptable estimated speed for the selected workload.

Best improvement path

Performance by workload

Workload	Grade	Fit	Decode	TTFT	Context
Chat	B	Runs well	36.7 tok/s	2875 ms	26K
Coding	B	Tight fit	34.2 tok/s	5665 ms	26K
Agentic Coding	C	Runs with offload (needs ~0.6 GB host RAM)	23.8 tok/s	11819 ms	26K
Reasoning	B	Tight fit	36.7 tok/s	6228 ms	26K
RAG	C	Runs with offload (needs ~0.6 GB host RAM)	23.8 tok/s	14774 ms

Quantization options

How Phi 3 Medium 14B (14B params) fits at each quantization level on RX 6900 XT 16GB (16.0 GB usable).

Quant	Bits	VRAM	Quality	Fit
Q2_K	2	5.5 GB	Low	B60
Q3_K_S	3	6.9 GB	Low	B62
NVFP4	4

Get started

Copy-paste commands to run Phi 3 Medium 14B on your machine.

Run

ollama run phi3:medium

Upgrade options

Hardware that runs Phi 3 Medium 14B well

RX 7900 XT 20GBBudget pick

20 GB VRAM (+4)800 GB/s (+288)

Raises estimated decode speed by about 65%.60.4 tok/s decode

Raises estimated decode speed by about 65%.

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

~$899 MSRP

RX 7900 XTX 24GBBest value

24 GB VRAM (+8)960 GB/s (+448)

Raises estimated decode speed by about 137%.87 tok/s decode

Raises estimated decode speed by about 137%.

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

~$999 MSRP

AMD Instinct MI60 32GBAMD upgrade

32 GB VRAM (+16)1024 GB/s (+512)

Raises estimated decode speed by about 72%.63.2 tok/s decode

Raises estimated decode speed by about 72%.

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

~$8,999 MSRP

Frequently asked questions

Can RX 6900 XT 16GB run Phi 3 Medium 14B?

Yes, RX 6900 XT 16GB can run Phi 3 Medium 14B with a B grade (Tight fit). Expected decode speed: 34.2 tok/s.

How much VRAM does Phi 3 Medium 14B need?

Phi 3 Medium 14B (14B parameters) requires approximately 14.1 GB of memory with Q4_K_M quantization.

What is the best quantization for Phi 3 Medium 14B?

The recommended quantization for Phi 3 Medium 14B is Q4_K_M, which balances quality and memory efficiency.

What speed will Phi 3 Medium 14B run at on RX 6900 XT 16GB?

On RX 6900 XT 16GB, Phi 3 Medium 14B achieves approximately 34.2 tokens per second decode speed with a time-to-first-token of 5665ms using Q4_K_M quantization.

Can RX 6900 XT 16GB run Phi 3 Medium 14B for coding?

For coding workloads, Phi 3 Medium 14B on RX 6900 XT 16GB receives a B grade with 34.2 tok/s and 26K context.

What context window can Phi 3 Medium 14B use on RX 6900 XT 16GB?

On RX 6900 XT 16GB, Phi 3 Medium 14B can safely use up to 26K tokens of context. The model's official context limit is 128K, but available memory constrains the safe maximum.

See all results for RX 6900 XT 16GB See all hardware for Phi 3 Medium 14B

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