What's the difference between thunderbolt 4 and thunderbolt 3?

Differences between Thunderbolt 4, USB 4, Thunderbolt 3, and USB 3

Intel has released the full specifications for Thunderbolt 4, the successor to Thunderbolt 3 that was first announced earlier this year. As previously stated, Thunderbolt 4 will not offer a speed increase over Thunderbolt 3 -- it will, however, still represent an important upgrade for the protocol.

Intel released the minimum system specifications for Thunderbolt 4 on Wednesday, July 8, explaining that it will feature USB4 compliance in addition to 'expanded capabilities.' Notable changes introduced by Thunderbolt 4 will include double the data and video minimum requirements compared to Thunderbolt 3, requiring minimum support for two 4K displays or a single 8K display.

As well, Thunderbolt 4 will offer the full 40Gb/s speed of Thunderbolt 3 with cables up to 2m (6.5ft) in length. Whereas Thunderbolt 3 has minimum support of 16Gb/s for PCIe connections, Thunderbolt 4 will boost this to 32Gb/s. When it comes to USB4 (which uses the same USB-C connector), speeds top out at 20Gb/s with 7.5W of power delivery and support for a single 4K display.

Beyond that, Thunderbolt 4 will require Intel VT-d DMA protection and support for accessories like docks that have four Thunderbolt ports. Other minimum requirements include that Thunderbolt 4 docks must wake the PC from sleep and that notebooks requiring less than 100W of power must include at least one Thunderbolt 4 port for charging.

Though it's clear at this point that Thunderbolt 4 won't offer faster speeds than Thunderbolt 3, it is ultimately an upgrade over the current specification, offering double the minimum requirements in some cases. As expected, Intel says it is working closely with manufacturers on the Thunderbolt 4 certification standards.

Talking about this is storage company Kensington's VP Ben Thacker, who said:

We expect Thunderbolt 4 products to be an inflection point for accessory makers who depend on PCs and Macs to offer an industry-leading set of product capabilities for a consistent user experience. The advancements in Thunderbolt 4 will help Kensington redefine the modern workspace of the future.

Consumers will benefit from the new minimum specifications, including the future arrival of faster Thunderbolt 4 drives, guaranteed support for two external 4K monitors and the ability to charge a slim notebook from at least one of the Thunderbolt 4 ports. These likewise exceed that of the USB4 spec, which uses the same port as Thunderbolt 3 and 4.