Microsoft launches compact local AI monster with 128 GB unified memory

Microsoft has officially launched the Surface RTX Spark Dev Box, a compact Windows 11 workstation built specifically for local AI development. It will likely be the gold standard for many RTX Spark-powered mini-PCs as a part of Microsoft's Project Zenith discussed earlier. At its heart is Nvidia's RTX Spark platform, combining an Arm-based Grace CPU and Blackwell RTX GPU with 6,144 CUDA cores and a single 128 GB memory pool shared between the processor and graphics hardware.

Microsoft says the Dev Box can locally run models with more than 120 billion parameters and context windows reaching one million tokens, while also tackling model fine-tuning, inference and long-running agentic workloads that would ordinarily require a cloud GPU instance. Nvidia rates the system for up to one petaflop of FP4 AI performance. The Surface RTX Spark Dev Box exists to keep grunt work local and reserve expensive frontier models for jobs that actually need them. Running smaller coding models and agents on-device eliminates the recurring token cost of sending every routine task to a cloud service, while 128 GB of unified memory gives the GPU more room to work compared to a consumer graphics card, although the performance will be affected by memory bandwidth bottlenecks.

Connectivity includes two USB-C ports, one USB-A port, full-size HDMI, RJ45 Ethernet and a 3.5 mm headphone jack, alongside a dedicated power input. Microsoft has not yet disclosed the USB, HDMI or Ethernet link speeds. The hardware has been designed around sustained workloads, with an anodised aluminium enclosure that doubles as part of the cooling system, allowing the Dev Box to handle long-running inference, training and agentic workloads without needing a full-sized workstation chassis.

The Surface RTX Spark Dev Box ships with a dev-centric Windows 11 Pro build. Developer Mode is enabled, PowerShell 7 is the default shell, WSL 2 comes configured with GPU passthrough and CUDA support, and tools including Visual Studio Code, Git, GitHub Copilot, Python and Node.js are pre-installed. Microsoft also strips back parts of the conventional Windows experience, removing Widgets, simplifying the taskbar and enabling Do Not Disturb by default. Microsoft has not explicitly labelled the Surface RTX Spark Dev Box as a Project Zenith product, but it clearly comes from the same school of thought. Its 128 GB memory capacity comfortably clears Zenith's minimum, and the preconfigured Windows environment mirrors much of what Microsoft subsequently formalised under the Zenith banner.

Microsoft has priced the Surface RTX Spark Dev Box at $5,999. For that price, you get 128 GB of unified memory and 2 TB of storage-twice as much as a similarly priced Surface Laptop Ultra would get you. It will be available for purchase later this year.