USB-C, Thunderbolt 4 & Thunderbolt 5 — same hole, four different speeds, three power tiers.

Connector vs protocol — the source of all confusion

USB-C is a connector shape. A small reversible oval with 24 pins, defined by the USB Implementers Forum in 2014. That's all it specifies — the plug, the socket, the pin layout. It says nothing about speed, power or video.

USB4, Thunderbolt 4 and Thunderbolt 5 are protocols. They define how data moves through those 24 pins. The same physical USB-C port can run any of the following protocols, depending on what's wired up behind it:

• USB 2.0 — 480 Mbps. Yes, in 2026, some "USB-C" ports on cheap monitors and accessories still run only USB 2.0.
• USB 3.2 Gen 1 — 5 Gbps. Common on budget laptops as the secondary USB-C port.
• USB 3.2 Gen 2 — 10 Gbps. Mid-range laptop standard.
• USB 3.2 Gen 2×2 — 20 Gbps. Used on some Asus and HP business laptops; not as common as it should be.
• USB4 v1 — 20 or 40 Gbps. Most premium 2023-2025 laptops.
• USB4 v2 — 80 Gbps. 2026 flagship laptops.
• Thunderbolt 3 — 40 Gbps. Intel-licensed predecessor that became USB4's foundation.
• Thunderbolt 4 — 40 Gbps, with mandatory feature set.
• Thunderbolt 5 — 80 Gbps symmetric / 120 Gbps display-asymmetric.

The USB 3.2 naming disaster

The USB-IF made an inexplicable decision in 2019 to rename every existing USB 3.x spec under the "USB 3.2" umbrella. The result is the most confusing naming convention in modern computing:

The USB-IF then tried to fix this in 2022 by introducing the "USB 5Gbps", "USB 10Gbps", "USB 20Gbps", "USB 40Gbps" and "USB 80Gbps" marketing labels. The numeric labels are actually useful — but most laptop manufacturers still list spec sheets with the old "Gen 1/2/2×2" naming. Both will exist in retail listings through 2027.

USB4 — Thunderbolt set free

USB4 is what happened when Intel donated Thunderbolt 3's underlying protocol to the USB-IF as royalty-free. It uses the same physical layer as TB3 (and TB4), the same 40 Gbps signalling, the same tunnelling architecture for DisplayPort and PCIe — but is open and freely implementable.

USB4 has two relevant versions in 2026:

• USB4 v1 (2019, refreshed 2022) — 20 Gbps or 40 Gbps. Mandatory DisplayPort Alt Mode, optional PCIe tunnelling.
• USB4 v2 (2023, broadly shipping 2026) — 80 Gbps symmetric or 120 Gbps asymmetric. Mandatory DisplayPort 2.1, mandatory PCIe tunnelling at higher tiers.

USB4 v2 and Thunderbolt 5 are functional twins at the silicon level. The distinction lies in certification: Thunderbolt 5 mandates a stricter feature set (minimum PD wattage, minimum simultaneous high-bandwidth peripherals, daisy-chain support) that USB4 v2 leaves optional. So a "USB4 v2" port might do everything a TB5 port does — or it might cap at the basics.

Thunderbolt 4 vs Thunderbolt 5 — what changed

The two big TB5 jumps: the bandwidth doubles (more on the asymmetric 120 Gbps below), and the PCIe lane upgrades to 4.0 ×4 — which is what makes eGPUs realistic on this generation. PCIe 4.0 ×4 is enough to feed a mid-range modern GPU without crippling it.

About that asymmetric 120 Gbps: Thunderbolt 5's "bandwidth boost" mode dynamically reallocates lanes — 120 Gbps to the display, 40 Gbps back to host — when paired with a DP 2.1 monitor that requests it. It's not a true 120 Gbps symmetric link; it's a clever way to feed an 8K 60Hz or 4K 240Hz panel without compromising data bandwidth.

Power Delivery — when 240W matters

USB Power Delivery (PD) is the negotiation protocol that lets devices request specific voltages and currents over USB-C. The current spec supports up to 240W via the EPR (Extended Power Range) addition, doubling the previous 100W ceiling.

240W matters because gaming laptops finally don't need barrel jacks. A Razer Blade 16 or Lenovo Legion 9i with TB5 can charge over a single USB-C cable from a 240W GaN brick — same connector as your phone, just a different cable rating.

DisplayPort Alt Mode — when USB-C carries video

DisplayPort Alt Mode lets a USB-C cable carry a DisplayPort video signal alongside USB data, by reassigning some of the 24 pins. It's how most "USB-C to monitor" connections work in 2026.

Three things to know:

• Not every USB-C port supports DP Alt Mode. Some ports are data-and-power-only. Check the port icon — a small monitor or DisplayPort logo confirms video support.
• Bandwidth shares with USB data. A USB4 v1 port doing 4K 60Hz HDR uses about half its 40 Gbps on video; the other half remains for USB.
• Thunderbolt always supports video. If the port has the Thunderbolt lightning bolt icon, video output is guaranteed.

There's also HDMI Alt Mode (specified but extremely rare in laptops — never standardised) and MHL Alt Mode (mostly dead). For practical purposes, DP Alt Mode is the only video standard you'll meet over USB-C.

eGPU in 2026 — realistic finally?

For years, external GPUs over Thunderbolt have been a "kind of works" category. Performance penalties of 25-35% versus internal PCIe, finicky driver setups, and Apple's eGPU drop on Apple Silicon all kept eGPUs in the niche tinkerer category.

Thunderbolt 5 changes the realistic ceiling. Sustained PCIe 4.0 ×4 bandwidth is enough to feed an RTX 5070 or RX 9070 with only marginal performance loss (5-15% versus the same GPU in a desktop PCIe 5.0 slot). For laptop users who want desktop-class gaming at home but a slim travel laptop, this finally works in 2026.

Current state of play:

• Windows on Intel/AMD x86 with TB5 — best eGPU experience. Driver maturity is solid; setups like Razer Core X V2 and ASUS XG Mobile work well.
• Windows with TB4 — still viable for RTX 4070-class GPUs and below. Performance ~70-80% of internal.
• Apple Silicon M4 with TB5 — supports DisplayLink and display chaining beautifully, but eGPU compute remains restricted. Apple still gates GPU drivers internally.
• ChromeOS / Linux — partial eGPU support; depends on distro and kernel version.

How to actually read a laptop spec sheet

Here's the practical lookup pattern for any laptop you're considering — applies equally to a R12,000 ultrabook and a R65,000 mobile workstation:

• Look for explicit "Thunderbolt 4" or "Thunderbolt 5" labels. Anything with that label is certified to a known feature set.
• If it says "USB-C with DisplayPort" — assume USB 3.2 Gen 2 (10 Gbps) unless explicitly stated otherwise.
• If it says "USB4" — check if it's v1 (40 Gbps) or v2 (80 Gbps). The marketing label "USB4 40Gbps" or "USB4 80Gbps" tells you.
• Look at the PD wattage. Some laptops have USB-C charging but only at 65W or 100W — they need a dedicated cable spec.
• Count Thunderbolt ports specifically. A laptop with three USB-C ports might only have one TB port; the others are slower.

SA pricing — dock and cable reality

Key takeaways

• USB-C is the plug. USB4, Thunderbolt 4 and Thunderbolt 5 are protocols — same hole, very different speeds.
• USB4 v2 (80 Gbps) and Thunderbolt 5 (80 / 120 Gbps async) are functional twins; TB5 mandates a stricter feature set.
• 240W charging requires a PD EPR-rated cable. Most USB-C cables only handle 60-100W.
• DisplayPort Alt Mode is how USB-C carries video — but not every USB-C port supports it.
• Thunderbolt 5 finally makes eGPU realistic — PCIe 4.0 ×4 closes the gap to internal GPUs.

Frequently asked questions