Can Llama 3.3 70B Instruct run on RX 6900 XT 16GB?

Q: What should I upgrade first if Llama 3.3 70B Instruct feels slow on RX 6900 XT 16GB?

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

Llama 3.3 70B Instruct needs ~53.4 GB but RX 6900 XT 16GB only has 16.0 GB. Try a smaller quantization or lighter model.

Runtime: llama.cppCapacity: No fitBandwidth: MediumStack: 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) — 53.4 GB, exceeds 16.0 GB available

53.4 GB required16.0 GB available

334% VRAM needed

37.4 GB over capacity — needs offload or smaller quantization

Fit status

Too heavy

Decode

2.0 tok/s

TTFT

96800 ms

Safe context

Memory

53.4 GB / 16.0 GB

Offload

70%

Memory breakdown

Weights42.7 GB

KV Cache8.2 GB

Runtime0.9 GB

Headroom1.6 GB

See how fast it feels

With memory offload — actual speed may be lower

See how fast it feelsLlama 3.3 70B Instruct on RX 6900 XT 16GB
1st promptCold start — includes initialization
>What is local AI inference?
Local AI inference means running an AI language model directly on your own hardware — your laptop, desktop, or server — instead of sending requests to a remote cloud API.

When you run inference locally the model weights are loaded into your GPU or unified memory. Each token you generate requires reading those weights from memory, so memory bandwidth is the main bottleneck for decode speed.

Key benefits of running locally:
  - Full privacy: your prompts never leave your machine
  - No per-token cost or rate limits
  - Works offline once the model is downloaded
  - Latency depends only on your hardware
2nd promptWarm — model ready, no init overhead
>How much VRAM do I need?
It depends on the model size and quantization level. A rough rule of thumb:

  Model size     Q4 (4-bit)    Q8 (8-bit)    FP16
  7B params      ~4.3 GB       ~7.5 GB       ~14 GB
  13B params     ~7.9 GB       ~13.9 GB      ~26 GB
  70B params     ~42.7 GB      ~74.9 GB      ~140 GB

Most people use 4-bit quantization (Q4_K_M) which gives 90-95% of full quality at a fraction of the memory. A 24 GB GPU can comfortably run most 7B-13B models.
Estimated: 2.0 tok/s decode · 96.8s TTFT (warm) · 5 tok/s prefill

What limits this setup

Usable VRAM is the main blocker for this model.

Not enough usable memory

The model needs 53.4 GB, but this setup only exposes 16.0 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	2.0 tok/s	52800 ms	4K
Coding	F	Too heavy	2.0 tok/s	96800 ms	4K
Agentic Coding	F	Too heavy	2.0 tok/s	140800 ms	4K
Reasoning	F	Too heavy	2.0 tok/s	114400 ms	4K
RAG	F	Too heavy	2.0 tok/s	176000 ms	4K

Quantization options

How Llama 3.3 70B Instruct (70B params) fits at each quantization level on RX 6900 XT 16GB (16.0 GB usable).

Quant	Bits	VRAM	Quality	Fit
Q2_K	2	27.3 GB	Low	F0
Q3_K_S	3	34.3 GB	Low	F0
NVFP4	4

Upgrade options

Hardware that runs Llama 3.3 70B Instruct well

Radeon Pro W7900 48GBBest value

48 GB VRAM (+32)864 GB/s (+352)

Makes the model fit on the accelerator instead of staying completely out of reach.6.3 tok/s decode

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

Raises estimated decode speed by about 215%.

~$3,999 MSRP

Radeon PRO W7900 DS 48GBAMD upgrade

48 GB VRAM (+32)864 GB/s (+352)

Makes the model fit on the accelerator instead of staying completely out of reach.6.3 tok/s decode

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

Raises estimated decode speed by about 215%.

~$3,999 MSRP

AMD Instinct MI350X 288GBBudget pick

288 GB VRAM (+272)8000 GB/s (+7488)

Makes the model fit on the accelerator instead of staying completely out of reach.136.8 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

NVIDIA H100 80GBBiggest leap

80 GB VRAM (+64)3350 GB/s (+2838)

Makes the model fit on the accelerator instead of staying completely out of reach.65.9 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.

~$40,000 MSRP

Frequently asked questions

Can RX 6900 XT 16GB run Llama 3.3 70B Instruct?

No, Llama 3.3 70B Instruct requires more memory than RX 6900 XT 16GB provides.

How much VRAM does Llama 3.3 70B Instruct need?

Llama 3.3 70B Instruct (70B parameters) requires approximately 53.4 GB of memory with Q4_K_M quantization.

What is the best quantization for Llama 3.3 70B Instruct?

The recommended quantization for Llama 3.3 70B Instruct is Q4_K_M, which balances quality and memory efficiency.

What speed will Llama 3.3 70B Instruct run at on RX 6900 XT 16GB?

On RX 6900 XT 16GB, Llama 3.3 70B Instruct achieves approximately 2.0 tokens per second decode speed with a time-to-first-token of 96800ms using Q4_K_M quantization.

Can RX 6900 XT 16GB run Llama 3.3 70B Instruct for coding?

For coding workloads, Llama 3.3 70B Instruct on RX 6900 XT 16GB receives a F grade with 2.0 tok/s and 4K context.

What context window can Llama 3.3 70B Instruct use on RX 6900 XT 16GB?

On RX 6900 XT 16GB, Llama 3.3 70B Instruct can safely use up to 4K tokens of context. The model's official context limit is —, but available memory constrains the safe maximum.

What should I upgrade first if Llama 3.3 70B Instruct feels slow on RX 6900 XT 16GB?

See all results for RX 6900 XT 16GB See all hardware for Llama 3.3 70B Instruct

Embed this result▼

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

<iframe src="https://willitrunai.com/embed/hf-maziyarpanahi--llama-3-3-70b-instruct-gguf-on-rx-6900-xt-16gb" width="400" height="180" frameborder="0" style="border:none;border-radius:12px;overflow:hidden;" title="Will It Run AI — fit result"></iframe>

Preview: