# Comma.ai Launches a PCIe Gen4 X4 to USB4 Dock with Open-Source Firmware

> Source: <https://comma.ai/shop/chestnut>
> Published: 2026-08-13 07:10:08+00:00

### With a PC

#### USB4

Connect chestnut to your computer and use it like any other USB4 dock.

#### USB3 or USB2

Use [tinygrad](https://github.com/tinygrad/tinygrad)
to access the GPU over a USB3 or USB2 connection.

#### Mac

Follow the [TinyGPU setup guide](https://docs.tinygrad.org/tinygpu/)
to use a supported GPU on macOS.

Join the #gpu-on-usb channel on the tinygrad [Discord](https://discord.gg/ZjZadyC7PK).