AMD RX 6900 XT 16GB vs AMD Strix Halo 128GB for local LLMs
2 reports on the AMD RX 6900 XT 16GB and 82 on the AMD Strix Halo 128GB
Which is faster for local LLMs?
Nobody has reported the same model at the same quant on both cards yet, so there's no measured head-to-head. Memory bandwidth, which caps how fast a card can write, is 2.0x higher on the AMD RX 6900 XT 16GB (512 GB/s on the AMD RX 6900 XT 16GB, 256 on the AMD Strix Halo 128GB). The estimates below compare them on the models people run most.
- Memory
- 16GB
- Memory bandwidth
- 512 GB/s
- FP16 compute
- 46.1 TFLOPS
- Reports
- 2
- Memory
- 128GB unified
- Memory bandwidth
- 256 GB/s
- FP16 compute
- 59 TFLOPS
- Reports
- 82
Estimated by the calculator
The quant the calculator recommends for each card and its estimated speed at a 32,768-token context with 32 GB of system RAM, from memory bandwidth and the model's shape.
| Model | AMD RX 6900 XT 16GB | AMD Strix Halo 128GB |
|---|---|---|
| Qwen3.8 27B | 33.4 t/sQ2_K | 3.5 t/sFP16 |
| Qwen3.8 125B · 6B active | doesn't fit at these settings | 12.6 t/sQ6_K |
| DeepSeek V4 Flash 284B · 13B active | doesn't fit at these settings | 33.5 t/sQ2_K |
| Qwen3.6 35B · 3B active | 110.4 t/sQ2_K | 12.6 t/sFP16 |
| Qwen3.6 27B | 33.4 t/sQ2_K | 3.5 t/sFP16 |
| Gemma 4 26B · 4B active | 74.4 t/sQ3_K_S | 9.5 t/sFP16 |
Change the context, RAM or model in the calculator: AMD RX 6900 XT 16GB · AMD Strix Halo 128GB
Every report on each card, with its source: AMD RX 6900 XT 16GB · AMD Strix Halo 128GB