Falcon 40B Instruct needs ~20.6 GB VRAM. RX 7900 XT 20GB has 20.0 GB. With Q2_K quantization, expect ~20 tok/s.
Operating mode
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.
Select quantization to explore
13.8 GB over capacity — needs offload or smaller quantization
Fit status
Too heavy
Decode
4.6 tok/s
TTFT
42219 ms
Safe context
4K
Memory
33.8 GB / 20.0 GB
Offload
40%
This setup is broadly balanced for this model.
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.
Buy headroom, not only minimum fit
A slightly larger memory tier gives you safer context growth and makes the recommendation more future-proof.
| Workload | Grade | Fit | Decode | TTFT | Context |
|---|---|---|---|---|---|
| Chat | F | Too heavy | 4.5 tok/s | 23638 ms | 4K |
| Coding | F | Too heavy | 4.6 tok/s | 42219 ms | 4K |
| Agentic Coding | F | Too heavy | 4.1 tok/s | 68615 ms | 4K |
| Reasoning | F | Too heavy | 4.6 tok/s | 49895 ms | 4K |
| RAG | F | Too heavy | 4.1 tok/s | 85769 ms | 4K |
How Falcon 40B Instruct (40B params) fits at each quantization level on RX 7900 XT 20GB (20.0 GB usable).
| Quant | Bits | VRAM | Quality | Fit |
|---|---|---|---|---|
Q2_K | 2 | 15.6 GB | Low | F0 |
Q3_K_S | 3 | 19.6 GB | Low | F0 |
NVFP4 | 4 |
Copy-paste commands to run Falcon 40B Instruct on your machine.
Run
docker run --rm -it ghcr.io/ggerganov/llama.cpp:full \
--hf-repo "tiiuae/falcon-40b-instruct" \
--hf-file "falcon-40b-instruct-Q5_K_M.gguf" \
-c 4096 -ngl 99Upgrade options
Makes the model fit on the accelerator instead of staying completely out of reach.
Raises estimated decode speed by about 100%.
~$1,899 MSRP
Makes the model fit on the accelerator instead of staying completely out of reach.
Raises estimated decode speed by about 48%.
~$2,249 MSRP
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.
~$3,999 MSRP
Yes, RX 7900 XT 20GB can run Falcon 40B Instruct at Q2_K quantization (Runs with offload (needs ~0.5 GB host RAM)). The recommended Q5_K_M requires 33.8 GB which exceeds available memory, but at Q2_K it needs only 20.6 GB. Expected decode speed: 20.0 tok/s.
Falcon 40B Instruct (40B parameters) requires approximately 33.8 GB at Q5_K_M quantization. On RX 7900 XT 20GB, it fits at Q2_K using 20.6 GB.
The recommended quantization is Q5_K_M, but on RX 7900 XT 20GB the best fitting quantization is Q2_K, which uses 20.6 GB.
On RX 7900 XT 20GB, Falcon 40B Instruct achieves approximately 20.0 tokens per second decode speed with a time-to-first-token of 9689ms using Q2_K quantization.
For coding workloads, Falcon 40B Instruct on RX 7900 XT 20GB receives a F grade with 4.6 tok/s and 4K context.
On RX 7900 XT 20GB, Falcon 40B Instruct can safely use up to 8K tokens of context at Q2_K quantization. The model's official context limit is 8K, but available memory constrains the safe maximum.
Paste this snippet into any page to show a live fit card.
<iframe src="https://willitrunai.com/embed/falcon-40b-instruct-on-rx-7900-xt-20gb" width="400" height="180" frameborder="0" style="border:none;border-radius:12px;overflow:hidden;" title="Will It Run AI — fit result"></iframe>
Preview:
| Medium |
| F0 |
Q4_K_M | 4 | 24.4 GB | Medium | F0 |
Q5_K_M | 5 | 28.8 GB | High | F0 |
Q6_K | 6 | 32.8 GB | High | F0 |
Q8_0 | 8 | 42.8 GB | Very High | F0 |
F16 | 16 | 82.0 GB | Maximum | F0 |
Buy headroom, not only minimum fit. A slightly larger memory tier gives you safer context growth and makes the recommendation more future-proof.