Thunderbolt 4

Thunderbolt 4. It is a high-speed hardware interface standard developed by Intel and introduced in 2020. Building upon the foundation of its predecessors, it mandates a minimum level of performance and capability for USB-C connectors, ensuring a consistent and powerful user experience. The standard is a key component of the Intel Evo platform specification for laptops and is designed to simplify connectivity for a wide range of peripherals and displays.

Overview

The development of this interface was announced by Intel in early 2020, with the first products receiving certification later that year. It is built upon the same underlying PCI Express and DisplayPort protocols as earlier versions but enforces stricter minimum requirements. A primary goal is to consolidate and streamline the capabilities of the modern USB-C port, reducing consumer confusion. The technology is central to the Intel Evo platform, a badge denoting premium laptop designs that meet specific performance and responsiveness targets.

Technical specifications

This standard requires a minimum of 40 Gigabit per second (Gbps) bidirectional bandwidth, identical to the maximum capability of Thunderbolt 3. It mandates support for at least two 4K DisplayPort displays or one 8K display. The specification requires PCI Express (PCIe) data transfer at 32 Gbps, doubling the minimum requirement from the previous generation. It also includes mandatory support for USB4, USB Power Delivery (up to 100W), and Wake-on-LAN from a connected dock. Physical security is enhanced through mandatory Intel VT-d-based direct memory access (DMA) protection.

Comparison with previous versions

While sharing the same 40 Gbps maximum speed as Thunderbolt 3, this newer standard imposes several critical minimum requirements that were optional before. For example, Thunderbolt 3 ports could be implemented with as little as 16 Gbps of PCI Express bandwidth, whereas the new version requires the full 32 Gbps. Support for dual 4K displays is now mandatory, whereas earlier implementations might only support a single monitor. The inclusion of USB4 compatibility is also a required feature, creating a more unified ecosystem. Furthermore, the certification for docks and cables is more rigorous, ensuring consistent performance across all branded accessories.

Hardware requirements and compatibility

Implementation requires a compatible controller from Intel, such as the JHL8540 or JHL8340 series. The host system must provide the necessary PCI Express lanes and power delivery circuitry. It maintains full backward compatibility with all previous versions of Thunderbolt and USB standards, including USB 3.2 and USB 2.0. Cables certified for this standard are also fully compatible with USB4 devices and hosts. Notably, the Apple M1 chip, used in MacBook Air and MacBook Pro models, implemented a version of the technology with some limitations compared to the full Intel specification.

Applications and use cases

The primary application is in high-performance docking solutions for modern laptops, particularly those certified under the Intel Evo program. It enables users to connect multiple high-resolution monitors, fast external SSD storage arrays, and professional audio interfaces through a single cable. The standard is ideal for video editors working with footage from RED Digital Cinema cameras or for developers requiring rapid data transfer to network-attached storage units. Its power delivery capability also simplifies charging for devices like the Dell XPS or Lenovo ThinkPad series from a dock.

Certification and branding

All products using this technology must pass a rigorous validation process administered by Intel. Certified products are permitted to use the distinctive lightning bolt logo. The certification ensures that all ports, cables, and devices meet the strict mandatory performance and security standards. This branding is distinct from the USB Implementers Forum's certification for USB4, though the technologies are interoperable. Microsoft also requires this specific interface standard for its Surface Pro and Surface Laptop lines to guarantee a premium connectivity experience.