M3 Ultra 512GB vs AMD RX 9070 XT 16GB for local LLMs
41 reports on the M3 Ultra 512GB and 21 on the AMD RX 9070 XT 16GB
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 28% higher on the M3 Ultra 512GB (819 GB/s on the M3 Ultra 512GB, 640 on the AMD RX 9070 XT 16GB). The estimates below compare them on the models people run most.
M3 Ultra 512GB
- Memory
- 512GB unified
- Memory bandwidth
- 819 GB/s
- FP16 compute
- 28.4 TFLOPS
- Reports
- 41
AMD RX 9070 XT 16GB
- Memory
- 16GB
- Memory bandwidth
- 640 GB/s
- FP16 compute
- 195 TFLOPS
- Reports
- 21
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 | M3 Ultra 512GB | AMD RX 9070 XT 16GB |
|---|---|---|
| Qwen3.8 27B | 8.0 t/sFP16 | 41.7 t/sQ2_K |
| Qwen3.8 125B · 6B active | 13.6 t/sFP16 | doesn't fit at these settings |
| Qwen3.6 35B · 3B active | 28.7 t/sFP16 | 138.0 t/sQ2_K |
| DeepSeek V4 Flash 284B · 13B active | 22.6 t/sQ8_0 | doesn't fit at these settings |
| Qwen3.6 27B | 8.0 t/sFP16 | 41.7 t/sQ2_K |
| Gemma 4 26B · 4B active | 21.5 t/sFP16 | 93.0 t/sQ3_K_S |
Change the context, RAM or model in the calculator: M3 Ultra 512GB · AMD RX 9070 XT 16GB
Every report on each card, with its source: M3 Ultra 512GB · AMD RX 9070 XT 16GB