NVIDIA DGX Spark vs M3 Ultra 256GB for local LLMs
57 reports on the NVIDIA DGX Spark and 6 on the M3 Ultra 256GB
Which is faster for local LLMs?
On Qwen3.8 125B · 6B active at 4-bit, the NVIDIA DGX Spark runs at 29.8 tokens per second (2 runs) and the M3 Ultra 256GB at 25.7 (one run). Those are community reports whose engines and settings differ, so the gap is a rough sign, not a controlled measure of the two cards. Memory bandwidth, which caps how fast a card can write, is 3.0x higher on the M3 Ultra 256GB (273 GB/s on the NVIDIA DGX Spark, 819 on the M3 Ultra 256GB).
- Memory
- 128GB unified
- Memory bandwidth
- 273 GB/s
- FP16 compute
- 125 TFLOPS
- Reports
- 57
- Memory
- 256GB unified
- Memory bandwidth
- 819 GB/s
- FP16 compute
- 28.4 TFLOPS
- Reports
- 6
Measured on both
Median tokens per second from plain runs (one device, one request, no speculative decoding, the whole model in the device's memory) of the same model size at the same quant level. Engines and context lengths can still differ between the runs. How to read these
| Model | NVIDIA DGX Spark | M3 Ultra 256GB |
|---|---|---|
| Qwen3.8 125B · 6B active4-bit | 29.82 runs | 25.7one run |
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. Where a model was also measured above, the measurement wins.
| Model | NVIDIA DGX Spark | M3 Ultra 256GB |
|---|---|---|
| Qwen3.8 125B · 6B active | 14.4 t/sQ6_K | 27.3 t/sQ8_0 |
| Qwen3.8 27B | 4.0 t/sFP16 | 8.0 t/sFP16 |
| DeepSeek V4 Flash 284B · 13B active | 38.3 t/sQ2_K | 36.0 t/sQ4_K_M |
| Qwen3.6 35B · 3B active | 14.5 t/sFP16 | 28.7 t/sFP16 |
| Qwen3.6 27B | 4.0 t/sFP16 | 8.0 t/sFP16 |
| Gemma 4 26B · 4B active | 10.8 t/sFP16 | 21.5 t/sFP16 |
| DeepSeek V4.1 Flash 552B · 16B active | doesn't fit at these settings | 48.0 t/sQ2_K |
Change the context, RAM or model in the calculator: NVIDIA DGX Spark · M3 Ultra 256GB
Every report on each card, with its source: NVIDIA DGX Spark · M3 Ultra 256GB