Running gpt-oss-120b on a Single DGX Spark
gpt-oss-120b, a 117B-parameter / 5.1B-active MXFP4 mixture-of-experts model, runs comfortably on a single NVIDIA DGX Spark (GB10, 128 GB unified memory). At ~63 GB of weights it leaves room for a 131K context window, and its reasoning quality makes it a useful deep-reasoning node alongside a faster mid-size daily driver. The catch is that the SM121 configuration is unforgiving. Several defaults and forum recommendations either silently corrupt output or refuse to start. This is the setup that actually works on the stock NGC container, and the traps that cost us the most time. ...