WizardLM 13B needs ~23.0 GB VRAM. RX 7900 XT 20GB has 20.0 GB. With Q4_K_M quantization, expect ~34 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
3.0 GB over capacity — needs offload or smaller quantization
Fit status
Very compromised (needs ~1 GB host RAM)
Decode
33.7 tok/s
TTFT
5743 ms
Safe context
8K
Memory
23.0 GB / 20.0 GB
Offload
10%
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.
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 {ram} GB of extra host RAM just for the offloaded portion, before OS and other tools.
| Workload | Grade | Fit | Decode | TTFT | Context |
|---|---|---|---|---|---|
| Chat | A | Tight fit | 60.5 tok/s | 1745 ms | 8K |
| Coding | B | Very compromised | 33.7 tok/s | 5743 ms | 8K |
| Agentic Coding | F | Too heavy | 13.8 tok/s | 20443 ms | 8K |
| Reasoning | B | Very compromised (needs ~1 GB host RAM) | 33.7 tok/s | 6787 ms | 8K |
| RAG | F | Too heavy | 13.8 tok/s | 25554 ms | 8K |
How WizardLM 13B (13B params) fits at each quantization level on RX 7900 XT 20GB (20.0 GB usable).
| Quant | Bits | VRAM | Quality | Fit |
|---|---|---|---|---|
Q2_K | 2 | 5.1 GB | Low | B68 |
Q3_K_S | 3 | 6.4 GB | Low | B68 |
NVFP4 | 4 | 7.3 GB | Medium | B69 |
Q4_K_M | 4 | 7.9 GB | Medium | B70 |
Q5_K_M | 5 | 9.4 GB | High | A71 |
Q6_K | 6 | 10.7 GB | High | A71 |
Q8_0Best for your GPU | 8 | 13.9 GB | Very High | A71 |
F16 | 16 | 26.7 GB | Maximum | F0 |
Copy-paste commands to run WizardLM 13B on your machine.
Run
lms load WizardLM-13B-V1.0 && lms server startUpgrade-Optionen
Removes host-memory offload, which is usually the single biggest latency and throughput win.
Raises estimated decode speed by about 159%.
ca. $999 MSRP
Removes host-memory offload, which is usually the single biggest latency and throughput win.
Raises estimated decode speed by about 41%.
ca. $1,899 MSRP
Removes host-memory offload, which is usually the single biggest latency and throughput win.
Adds memory headroom for longer context windows and future model growth.
ca. $2,249 MSRP
Yes, RX 7900 XT 20GB can run WizardLM 13B with a B grade (Very compromised). Expected decode speed: 33.7 tok/s.
WizardLM 13B (13B parameters) requires approximately 23.0 GB of memory with Q4_K_M quantization.
The recommended quantization for WizardLM 13B is Q4_K_M, which balances quality and memory efficiency.
On RX 7900 XT 20GB, WizardLM 13B achieves approximately 33.7 tokens per second decode speed with a time-to-first-token of 5743ms using Q4_K_M quantization.
For coding workloads, WizardLM 13B on RX 7900 XT 20GB receives a B grade with 33.7 tok/s and 8K context.
On RX 7900 XT 20GB, WizardLM 13B can safely use up to 8K tokens of context. The model's official context limit is 8K, but available memory constrains the safe maximum.
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.
Paste this snippet into any page to show a live fit card.
<iframe src="https://willitrunai.com/embed/wizardlm-13b-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: