ElectronicsInfoline

Will It Work? · Guide

Thunderbolt 3, 4, 5 and USB4: what each one guarantees

By Bulan Sarkar, founder of ElectronicsInfoline (since 2000)

Thunderbolt 3, Thunderbolt 4, Thunderbolt 5 and USB4 all use the USB-C connector, so the port alone tells you little. What separates them is what each one promises as a minimum. Here are those promises, quoted from Intel and the USB-IF.

Thunderbolt 3: 40 Gbit/s, one 5K or two 4K displays, laptop charging up to 100 W optional. Thunderbolt 4: 40 Gbit/s always, two 4K60 or one 8K60 display, PCIe at 32 Gbit/s, charging required on at least one port. Thunderbolt 5: 80 Gbit/s both ways (120 with Bandwidth Boost), up to 240 W charging available.

What each version promises

  • Thunderbolt 3: 40 Gbit/s, with two streams of DisplayPort 1.2 (Intel); one 5K or two 4K displays (Intel); notebook charging up to 100 W was optional, with 15 W for bus-powered devices (Intel).
  • Thunderbolt 4: always 40 Gbit/s (Intel); up to two 4K 60 Hz displays or one 8K 60 Hz (Intel); PCIe at 32 Gbit/s (Intel), up from 16 (Intel); PC charging on at least one port for laptops under 100 W (Intel); up to 15 W for accessories (Intel).
  • Thunderbolt 5: 80 Gbit/s both ways (Intel), up to 120 Gbit/s one way with Bandwidth Boost (Intel); PCIe at 64 Gbit/s (Intel); up to two 8K 60 Hz monitors per port through a dock (Intel); charging required up to 140 W and available up to 240 W (Intel).
Thunderbolt 3, 4 and 5: bandwidth and laptop chargingThunderbolt 3: 40 Gbit/s, laptop charging up to 100 W optional. Thunderbolt 4: 40 Gbit/s, up to 100 W. Thunderbolt 5: 80 Gbit/s, 120 Gbit/s with Bandwidth Boost, up to 240 W.BandwidthThunderbolt 340 Gbit/sThunderbolt 440 Gbit/sThunderbolt 580 Gbit/sLaptop charging, up toThunderbolt 3100 WThunderbolt 4100 WThunderbolt 5240 W
Figure 1. Intel's figures. Thunderbolt 5 can shift to 120 Gbit/s one way for displays (Bandwidth Boost). Charging on Thunderbolt 3 was optional; Thunderbolt 4 requires it on at least one port.

Where USB4 fits

USB4 is the USB-IF's standard on the same connector: up to 40 Gbit/s in its first version (USB-IF), up to 80 Gbit/s in version 2.0 (USB-IF), with an optional 120 Gbit/s one way (USB-IF). It tunnels DisplayPort and PCIe (USB-IF). Thunderbolt 4 complies with USB4 (Intel) and sets firmer minimums on top.

What each kind of USB-C port promises for video and chargingUSB-C, data only: video no video; charging see maker. USB-C + DP Alt Mode: video DP 1.2 / 1.4 / 2.1; charging see maker. Thunderbolt 3: video one 5K or two 4K; charging up to 100 W, optional. Thunderbolt 4: video two 4K60 or one 8K60; charging required, under 100 W. Thunderbolt 5: video two 8K60 (dock); charging up to 240 WPortVideoLaptop chargingUSB-C, data onlyno videosee makerUSB-C + DP Alt ModeDP 1.2 / 1.4 / 2.1see makerThunderbolt 3one 5K or two 4Kup to 100 W, optionalThunderbolt 4two 4K60 or one 8K60required, under 100 WThunderbolt 5two 8K60 (dock)up to 240 W
Figure 2. Same connector, different promises. Thunderbolt figures are Intel's minimums; for a plain USB-C port the computer maker's spec sheet is the only source.

Tips and tricks

  • A USB4 port’s display and charging support is up to the computer maker; check the spec sheet. Thunderbolt 4 makes them minimums.
  • For two 4K60 monitors from one port, Thunderbolt 4 is the version that promises it.
  • Thunderbolt 5’s 240 W is “available”, not required. Check the laptop and the dock for EPR support before counting on it.
  • Match the cable to the speed: the USB-IF ties 40 Gbit/s to cables certified for 40Gbps, and 80 Gbit/s to cables certified for 80Gbps.

What we would do

For one monitor and charging, a USB-C port with DisplayPort Alt Mode can be enough; check it in the hub and dock checker. For two 4K screens, fast external storage and charging through one cable, pick Thunderbolt 4 or 5 on both the laptop and the dock.

Questions people ask

Is Thunderbolt 4 faster than Thunderbolt 3? Not in headline speed: Intel says both run at 40 Gbit/s. Thunderbolt 4 raises the minimums instead: PCIe data at 32 Gbit/s (up from 16), two 4K displays at 60 Hz, and PC charging on at least one port.

Is USB4 the same as Thunderbolt 4? No. Intel says Thunderbolt 4 complies with the USB4 specification, and adds its own minimums. USB4 is the USB-IF’s standard: up to 40 Gbit/s in its first version and 80 Gbit/s in version 2.0, tunnelling DisplayPort and PCIe.

Can Thunderbolt 5 charge a laptop at 240 W? Intel says Thunderbolt 5 supports, but does not require, USB PD Extended Power Range, delivering up to 240 W; its tech brief lists charging as required up to 140 W.

Will a Thunderbolt dock work on a USB-C port without Thunderbolt? It depends on the dock. Its maker lists what works on a plain USB-C port, and the Thunderbolt display promises do not apply there.

Sources

Each figure on this page is quoted from the source below or worked out from them. Sources checked , each quote read again against the source in a second pass.

  1. Intel, Thunderbolt™ 3 brings Thunderbolt to USB-C (Thunderbolt 3 Overview slides): 40Gbps Thunderbolt · Four lanes of PCI Express Gen 3 · Two streams (eight lanes) of DisplayPort 1.2 · Integrated USB 10Gbps host controller thunderbolttechnology.net/sites/default/files/thunderbolt_3_…
  2. Intel, Thunderbolt™ 3 brings Thunderbolt to USB-C (Thunderbolt 3 Overview slides): Single-cable connection for one 5K or two 4K displays thunderbolttechnology.net/sites/default/files/thunderbolt_3_…
  3. Intel, Thunderbolt™ 3 brings Thunderbolt to USB-C (Thunderbolt 3 Overview slides): Optional - Notebook Charging up to 100W ... Standard - 15W to bus-powered devices thunderbolttechnology.net/sites/default/files/thunderbolt_3_…
  4. Intel, Introducing Thunderbolt 4: Universal Cable Connectivity for Everyone: Thunderbolt 4 always delivers 40 Gbps speeds and data, video and power over a single connection. intel.com/content/www/us/en/newsroom/news/thunderbolt-4-univ…
  5. Intel, Introducing Thunderbolt 4: Universal Cable Connectivity for Everyone: Double the minimum video and data requirements of Thunderbolt 3. intel.com/content/www/us/en/newsroom/news/thunderbolt-4-univ…
  6. Intel, What Is Thunderbolt™ 4 and How Is It Different from USB-C? – Intel: Up to two 4K 60 Hz displays or one 8K 60 Hz display on a single connection intel.com/content/www/us/en/architecture-and-technology/thun…
  7. Intel, Introducing Thunderbolt 4: Universal Cable Connectivity for Everyone: Data: PCIe at 32 Gbps for storage speeds up to 3,000 MBps. intel.com/content/www/us/en/newsroom/news/thunderbolt-4-univ…
  8. Intel, What Is Thunderbolt 4? - Intel: minimum PCIe data requirements have increased from 16Gbps to 32Gbps. intel.com/content/www/us/en/gaming/resources/upgrade-gaming-…
  9. Intel, Introducing Thunderbolt 4: Universal Cable Connectivity for Everyone: PC charging on at least one computer port ... For thin-and-light laptops that require less than 100 watts to charge. intel.com/content/www/us/en/newsroom/news/thunderbolt-4-univ…
  10. Intel, What Is Thunderbolt™ 4 and How Is It Different from USB-C? – Intel: Up to 100W of power for laptop charging and up to 15W for computer-powered accessories. intel.com/content/www/us/en/architecture-and-technology/thun…
  11. Intel, Introducing Thunderbolt 4: Universal Cable Connectivity for Everyone: expanded capabilities and USB4 specification compliance intel.com/content/www/us/en/newsroom/news/thunderbolt-4-univ…
  12. Intel, Thunderbolt™ Technology: A Universe of Possibilities: Thunderbolt™ 5 technology delivers up to 80 Gbps bidirectional bandwidth—2x vs. the previous generation intel.com/content/www/us/en/architecture-and-technology/thun…
  13. Intel, Technology Brief | Thunderbolt™ 5: Bandwidth Boost can rebalance the Thunderbolt link when the system needs high levels of video bandwidth, increasing the transmit speed to 120 Gbps, as illustrated in Figure 4. This provides up to 3x more video bandwidth than Thunderbolt 4, and up to 50% more video bandwidth than DisplayPort 2.1 (UHBR20). thunderbolttechnology.net/sites/default/files/Thunderbolt_5_…
  14. Intel, Technology Brief | Thunderbolt™ 5: With 64 Gbps of PCIe bandwidth, Thunderbolt 5 delivers 2x the data transfer speeds of Thunderbolt 4 thunderbolttechnology.net/sites/default/files/Thunderbolt_5_…
  15. Intel, Technology Brief | Thunderbolt™ 5: Thunderbolt 5 supports (but does not require) Extended Power Range (EPR) support, delivering up to 240 watts of power. thunderbolttechnology.net/sites/default/files/Thunderbolt_5_…
  16. Intel, Technology Brief | Thunderbolt™ 5: Required PC charging on at least one computer port | Required up to 140W / Available up to 240W (Thunderbolt 5) | Required up to 100W / Available up to 140W (Thunderbolt 4) thunderbolttechnology.net/sites/default/files/Thunderbolt_5_…
  17. Intel, Thunderbolt™ 5 for Gaming – Intel: One Thunderbolt 5 port can connect to up to two 8K 60Hz DisplayPort or HDMI monitors through a compatible dock or adapter. intel.com/content/www/us/en/learn/thunderbolt-5-for-gaming.h…
  18. USB-IF, USB-IF Announces Publication of USB4™ Specification (September 3, 2019): Two-lane operation using existing USB Type-C® cables and up to 40Gbps operation over 40Gbps certified cables usb.org/sites/default/files/2019-09/USB-IF_USB4%20spec%20ann…
  19. USB-IF, USB4® | USB-IF: Two-lane operation using existing USB Type-C cables and up to 80 Gbps operation over 80 Gbps certified cables usb.org/usb4
  20. USB-IF, USB-IF Announces Publication of New USB4® Specification to Enable USB 80Gbps Performance (October 18, 2022): Optionally for certain applications, such as driving very-high performance USB4-based displays, the USB Type-C signal interface can be configured asymmetrically to deliver up to 120Gbps in one direction while retaining 40Gbps in the other direction. usb.org/sites/default/files/2022-10/USB-IF%20USB%2080Gbps%20…
  21. USB-IF, USB Promoter Group Announces USB4® Version 2.0 (September 1, 2022): Protocol updates are also being made to enable higher performance USB 3.2, DisplayPort™ and PCI Express® (PCIe®) data tunneling to best use the higher available bandwidth. usb.org/sites/default/files/2022-09/USB%20PG%20USB4%20Versio…

Author: Bulan Sarkar · Report an error

Numbers here are quoted from standards bodies and makers, or worked out from them. Nothing on this page was measured or tested by us.