What is Thunderbolt 4? USB standard explained

Wondering what the fuss is about Thunderbolt 4? Well, here’s our quick guide and history behind Intel’s protocol and cables.

Thunderbolt is a connection protocol developed by Intel, in conjunction with Apple, with Thunderbolt 4 being the fourth iteration of it.

Thunderbolt 4 in a nutshell

Thunderbolt 4 is a much faster, but expensive connection type, offering faster speeds and better connectivity with a wider array of devices. Screens, storage, internet, and more can all be connected via hubs or some devices support a direct connection.

The main advantage of Thunderbolt is that it provides multiple services over one cable. While these will often go into hubs that have their own cables to other devices, it minimizes the need to bring everything directly into the laptop or desktop.

Thunderbolt 4 specifications

Spec	Thunderbolt 4 Technology	Thunderbolt 3 Technology
Connector type	USB-C	USB-C
Total bandwidth	40 Gbps	40 Gbps
Minimum bandwidth available for data transfer	32 Gbps	16 Gbps
Display	Up to two 4K monitors, or one 8K monitor	One 4K monitor
Thunderbolt ports per accessory	Up to four ports	Up to two ports
Laptop charging	Up to 100W on at least one computer port	Supported, but not required
System wake from sleep using connected accessory	Required	Supported, but not required
Intel VT-d-based direct memory access (DMA) protection	Required	Supported, but not required
USB4 specification	Compliant	Compatible

Data from Intel

The main difference between each Thunderbolt version is, outside the speed differences from 2 to 3, there’s more support for the singular cable to do.

Thunderbolt 4 is now capable of not only supporting 40Gb/s transfers over two meters of cable but can now support double the bandwidth for transfers.

On top of this, rather than just display a single 4K monitor, Thunderbolt 4 is able to support up to one 8K, or two 4K monitors.

By incorporating newer technology into Thunderbolt 4, Intel has managed to secure up to 100W laptop charging, as well as support for USB4 devices.

Is Thunderbolt 4 the same as USB-C?

Thunderbolt 4 uses the same connector design as USB-C and is backwards compatible with USB-C, but to use all of Thunderbolt 4’s features, you’ll need a dedicated port.

Can you use Thunderbolt 4 on AMD?

Thunderbolt 4 is available on Intel and Apple systems, however, has not yet been ported to AMD. Though, Thunderbolt 3 is available for AMD systems.

The suspected reason behind this, outside of licensing issues, is that the current USB4 spec is more than capable of providing a decent alternative to Thunderbolt.

USB4, however, cannot daisy chain as of yet.

Why are Thunderbolt cables expensive?

Due to it being a niche proprietary connection housing custom technology, Thunderbolt is much more expensive than USB.

Some cables are optical, while cheaper versions will feature copper. As of 2023, there’s still no sight of optical cables for 4.

However, the cables are split into two, active and passive. The longer the cable, the more ‘active’ hardware will need to be included so that the signal doesn’t slow down along the way.

Optical cables function differently from copper, so when it was introduced to 3, the maximum cable length hit two meters.

History

Before Thunderbolt there was FireWire, or IEEE 1394. This protocol was developed primarily by Sony, Panasonic, and Apple.

After a fairly tumultuous history, Apple decided to drop FireWire and work with Intel on producing a faster alternative to USB 3.0. At the time, USB 3.0 could only hit speeds of 4.8Gbit/s or 600 MB per second. Originally called Light Peak, could do 20Gb/s, as well as stream video and daisy chain to five other devices.

Originally demoed in 2009 by Intel, it was a large PCIe card and eventually in 2010, was shrunk to fit within a laptop. Apple, now working with Intel to supply chips for their line of computers and laptops, began to include Macs in 2011.

Thunderbolt 1 and 2 used modified mini DisplayPort connectors, before moving to USB-C style connectors for 3 and 4.