NVIDIA DGX Spark 128GB

NVIDIA’s 128GB Grace Blackwell desktop - a 1.2kg cube that puts datacenter-class memory capacity on a desk. Shipped October 2025 at a $4,699 MSRP (down from the $4,999 announced at GTC in March 2025). GB10 chip: 128GB LPDDR5X unified at 273 GB/s, 170W TDP, NVFP4 acceleration on the Blackwell GPU, ConnectX-7 networking built in.

What it does well:

• Capacity at low power: 128GB unified means 70B-class dense models at 8-bit or 200B-class MoE at 4-bit, on under 240W at the wall.
• Stacking: ConnectX-7 links two or more Sparks into one pool - community builds run 1x through 4x units, and the DGX Spark benchmarks guide has the measured numbers per stack size.
• NVFP4: Blackwell’s 4-bit format keeps quality high at the capacity-focused quants this memory tier wants.

Where it falls short: 273 GB/s is the binding constraint - decode speed per stream is a quarter of an RTX 5090’s, and the 128GB ceiling means the biggest open checkpoints do not fit even at 1-bit.

Run it locally: ships with DGX OS and day-one Ollama support; vLLM and SGLang cover the cluster builds. The modeldex results rank every seeded checkpoint by fit and estimated tok/s.