Castellan
System requirements
What your PC needs.
Castellan runs on Windows, and its local AI runs on the PC itself: on its NPU, its graphics card or its processor, whichever it has. Here's what it needs, and what each kind of PC gets.
- Windows
- Windows 11, version 24H2 or later
- Castellan is made for Windows 11 and tested on it. Its setup runs on .NET 10, which Microsoft supports on Windows 11 from version 24H2. Windows 10 isn't supported.
- Processor
- Any 64-bit processor: x64 or Arm64
- x64 for Intel and AMD, Arm64 for Snapdragon. Each has its own setup, and your account page offers the one for your PC.
- Memory
- 16 GB or more
- The local AI holds several gigabytes while it works, beside Windows and your own programs. An NPU and built-in graphics work from this memory too.
- Free space
- 20 GB
- The local AI's model servers and models take 2.5 to 14 GB, depending on this PC's NPU and graphics card. The rest is room for Castellan, its staff and their updates.
- Internet
- To set up, and for updates
- The setup downloads the local AI from its makers: several gigabytes, and it says how much and asks first. Day to day, the local AI runs on this PC, never online.
- Graphics card
- Optional
- NVIDIA, AMD, Intel or a Snapdragon's Adreno, with up-to-date drivers: a card of its own, or the graphics built into the processor.
Heiward, free on its own, has its own requirements: they're on its page.
Where the local AI runs
What each PC gets
The setup looks at this PC and sets the local AI up on what it has. It runs on the NPU first, then the graphics card, then the processor.
With a supported NPU
The local AI runs on the NPU first: quietly, on very little power, leaving the graphics card and processor free for you. What the NPU doesn't do goes to the graphics card or the processor.
The setup asks the NPU a test question and times it before it's used. If it doesn't answer, the graphics card or processor does the work.
With a graphics card
Everything the local AI does: it answers in words, describes pictures and searches by meaning. NVIDIA cards run it through CUDA; AMD, Intel and other cards through Vulkan; a Snapdragon's Adreno through OpenCL.
Built-in graphics share the PC's memory. A card of its own with 12 GB of memory or less leaves describing pictures off, so the rest fits. While a game uses the card, background work keeps off it.
With only a processor
The processor runs the local AI more slowly, and only answers in words: summaries, labels and names. Describing pictures and searching by meaning need an NPU or a graphics card.
NPUs
The NPUs it runs on
Tested means we ran Castellan's NPU check on that exact chip; expected, that it has the same NPU as a chip we tested, or a newer one whose settings we've estimated from them; untested, that the setup supports it but we haven't run it.
Snapdragon X
- TestedSnapdragon X2 Elite Extreme (X2E94100)
- ExpectedSnapdragon X2 Elite and X2 Plus, the other models
- UntestedSnapdragon X, X Plus and X Elite (the first generation)
Not supported: Snapdragon 8cx, 8c, 7c, SQ1–SQ3, 850 or 835 (Hexagon v68 or older). There, the graphics card or processor does the work.
Intel Core Ultra
- TestedIntel Core Ultra 7 256V
- TestedIntel Core Ultra 5 225U
- ExpectedIntel Core Ultra 200V, the other models
- ExpectedIntel Core Ultra Series 1, and the other 200U models
- ExpectedIntel Core Ultra 200S (desktop)
- ExpectedIntel Core Ultra Series 3
- ExpectedIntel Core Series 3
NPU driver: 32.0.100.4023 or later; 32.0.100.5540 for the Intel Core Ultra Series 3 and Intel Core Series 3.
AMD Ryzen AI
- TestedAMD Ryzen AI 7 350
- ExpectedAMD Ryzen AI 300, Ryzen AI Max and Ryzen AI 400, the other models
Not supported: Ryzen 7040/8040, Phoenix and Hawk Point (XDNA). There, the graphics card or processor does the work.
NPU driver: 32.0.203.311 or later.
Keep your NPU's driver up to date, from Windows Update or your PC maker's site: an NPU whose driver is older than the setup needs isn't used until it's updated, and the setup says so. A newer NPU the setup doesn't know yet is tried on cautious settings and kept only if it answers. Every supported chip, with our measurements.
Check your PC
Not sure what yours has?
Windows' Settings > System > About shows your processor, its installed memory (RAM), whether it's an x64-based or ARM-based PC, and your edition and version of Windows. Task Manager's Performance tab lists an NPU, on PCs that have one.