# USB-C and Thunderbolt - Universal Connectivity USB-C and Thunderbolt represent the industry's push toward **one cable for everything**: video, data, power, and peripherals. But the USB-C connector is just a physical shape—the actual capabilities depend on what protocol runs through it. This causes massive confusion when "USB-C" can mean anything from basic USB 2.0 speeds to 40 Gbps Thunderbolt 4 with dual 4K displays. ## USB-C: Just a Connector Shape The **USB-C connector** is a 24-pin reversible plug that replaced the rectangular USB-A and mini/micro-USB connectors. By itself, USB-C tells you nothing about: - **Data speed** (USB 2.0? USB 3.2? Thunderbolt?) - **Video capability** (DisplayPort Alt Mode? HDMI Alt Mode?) - **Power delivery** (5W charging? 240W laptop power?) **Think of USB-C like an electrical outlet**—you need to know what's wired behind it. ## USB-C Capabilities by Protocol ### USB 2.0 over USB-C - **Speed:** 480 Mbps (60 MB/s) - **Use case:** Cheap peripherals, keyboards, mice - **Power:** Up to 15W (5V @ 3A) - **Example:** Budget phone chargers, basic USB-C cables ### USB 3.2 Gen 1 (formerly USB 3.0) - **Speed:** 5 Gbps (625 MB/s) - **Use case:** External hard drives, USB hubs - **Power:** Up to 100W with USB-PD - **Cable requirements:** USB-C to USB-C with SuperSpeed wires ### USB 3.2 Gen 2 - **Speed:** 10 Gbps (1.25 GB/s) - **Use case:** Fast SSDs, pro video capture - **Power:** Up to 100W - **Example:** [Samsung T7 Portable SSD](https://www.bhphotovideo.com/c/product/1556831-REG/samsung_mu_pc1t0t_am_1tb_t7_portable.html) - Fast external storage over USB-C ### USB 3.2 Gen 2×2 - **Speed:** 20 Gbps (2.5 GB/s) - **Use case:** High-speed RAID enclosures - **Power:** Up to 240W (USB-PD 3.1) - **Cable requirements:** USB-C to USB-C with all SuperSpeed lanes active - **Rare:** Few devices support this as of 2025 ### USB4 (Gen 3) - **Speed:** 40 Gbps (5 GB/s) - **Protocol:** Based on Thunderbolt 3 spec, made royalty-free - **Mandatory features:** - DisplayPort 2.1 Alt Mode - USB-PD up to 240W - PCIe tunneling - **Backward compatible:** USB 3.2, USB 2.0, Thunderbolt 3/4 - **Example:** [CalDigit USB4 Element Hub](https://www.bhphotovideo.com/c/product/1776422-REG/caldigit_usb4_element_hub.html) - Pro-grade USB4 hub ## DisplayPort Alt Mode **Alt Mode** repurposes USB-C data lanes for video signals: - **4 lanes** dedicated to DisplayPort (up to DP 1.4: 25.92 Gbps) - **Remaining lanes** handle USB 3.x data simultaneously - **No adapter needed** for USB-C to DisplayPort/HDMI—just a cable **Example configuration:** - USB-C port → 4K @ 60Hz monitor + USB 3.1 data to hub - [Cable Matters USB-C to DisplayPort Cable](https://www.amazon.com/Cable-Matters-DisplayPort-USB-C-Supporting/dp/B01J6DT070) - Direct 4K @ 60Hz connection **Limitations:** - Can't run full 10 Gbps USB 3.2 + full 4K @ 120Hz simultaneously - USB4 allocates bandwidth dynamically—video gets priority ## Thunderbolt 3 **Thunderbolt 3** (released 2016) was Intel's proprietary protocol that used USB-C connector: - **Speed:** 40 Gbps total bandwidth - **Video:** DisplayPort 1.4 (up to two 4K @ 60Hz displays) - **Data:** PCIe Gen 3 ×4 tunneling (32 Gbps for eGPUs, NVMe drives) - **Power:** USB-PD up to 100W - **Daisy-chaining:** Up to 6 devices **Key feature:** **PCIe tunneling** allows external GPUs (eGPUs) and NVMe enclosures at near-internal speeds. **Example devices:** - [OWC Thunderbolt 3 Dock](https://www.bhphotovideo.com/c/product/1368735-REG/owc_thunderbolt_3_dock_14_port.html) - 14-port dock with dual 4K display support - [Razer Core X eGPU Enclosure](https://www.amazon.com/Razer-Core-Thunderbolt-External-Enclosure/dp/B07Q78VMPW) - Desktop GPU over Thunderbolt 3 **Intel's licensing:** Required certification fee (~$30/device), limiting adoption until USB4. ## Thunderbolt 4 **Thunderbolt 4** (released 2020) didn't increase speed but **raised minimum specs**: - **Speed:** 40 Gbps (same as TB3) - **Mandatory requirements:** - Two 4K displays OR one 8K display - PCIe data: 32 Gbps minimum (TB3 allowed 16 Gbps) - USB4 compliance - Wake from sleep via keyboard/mouse - **Intel VT-d DMA protection** (security against DMA attacks) **Why it matters:** TB3 was inconsistent—some ports couldn't power displays or lacked full PCIe. TB4 guarantees all features. **Example devices:** - [CalDigit TS4 Thunderbolt 4 Dock](https://www.bhphotovideo.com/c/product/1698748-REG/caldigit_ts4_18_port_thunderbolt.html) - 18 ports, 98W charging, dual 6K display support - [Plugable TBT4-UDZ Thunderbolt 4 Dock](https://www.amazon.com/Plugable-Thunderbolt-Charging-DisplayPort-Thunderbolt4/dp/B0C4RW1VR9) - Budget TB4 dock with dual 4K @ 60Hz ## USB4 vs Thunderbolt 4 | Feature | **Thunderbolt 4** | **USB4** | |---------|-------------------|----------| | **Speed** | 40 Gbps mandatory | 20 or 40 Gbps | | **DisplayPort** | DP 1.4 mandatory | DP 2.1 support optional | | **PCIe bandwidth** | 32 Gbps mandatory | Optional | | **Dual 4K displays** | Mandatory | Optional | | **Intel VT-d security** | Mandatory | Optional | | **Certification** | Intel certified | VESA/USB-IF certified | **Practical difference:** Thunderbolt 4 is **guaranteed spec**, USB4 is **minimum spec**. A USB4 port might only do 20 Gbps with no video support—always check device specs. ## Thunderbolt 5 (2024) Intel announced **Thunderbolt 5** in September 2023, first devices arriving 2024-2025: - **Speed:** 80 Gbps bidirectional, **120 Gbps** for video-heavy workloads - **Video:** DisplayPort 2.1—supports 8K @ 120Hz or triple 4K @ 144Hz - **PCIe Gen 4:** Faster eGPU and storage performance - **Power:** Up to 240W (USB-PD 3.1) **Use case:** 8K video editing, multiple high-refresh monitors, future-proofing pro workstations. **Example (future):** Intel-based workstations and docks shipping late 2025. ## Cable Confusion and Markings **The problem:** USB-C cables look identical but have vastly different specs. ### How to Identify Cable Capabilities **USB-IF certification logos:** - **USB 3.2 Gen 2:** SuperSpeed USB 10 Gbps logo - **USB4:** USB4 40 Gbps logo - **Thunderbolt 3:** ⚡ symbol + "3" - **Thunderbolt 4:** ⚡ symbol + "4" **Cable types:** - **USB 2.0 cable:** Charging only, no data/video (unless explicitly labeled) - **USB 3.2 Gen 1 cable:** 5 Gbps data, no video - **USB 3.2 Gen 2 cable:** 10 Gbps data, DisplayPort Alt Mode possible - **Thunderbolt 3 cable (passive):** 40 Gbps up to 0.5m (1.6 ft) - **Thunderbolt 3 cable (active):** 40 Gbps up to 2m (6.6 ft), includes signal booster - **Thunderbolt 4 cable:** 40 Gbps up to 2m, meets stricter EMI requirements **Power ratings:** - **60W cables:** Standard USB-C - **100W cables:** USB-PD certified, thicker wires - **240W cables:** USB-PD 3.1 (Extended Power Range) **Example certified cables:** - [Cable Matters USB4 Cable (3.3 ft)](https://www.amazon.com/Cable-Matters-Thunderbolt-Certified-Compatible/dp/B0B8X6MM2M) - Affordable USB4/TB4 cable - [Apple Thunderbolt 4 Pro Cable (1.8m)](https://www.bhphotovideo.com/c/product/1673038-REG/apple_mwp02am_a_thunderbolt_4_pro_cable.html) - Premium build, 1.8m active cable ## Single-Cable Laptop Docking **The holy grail:** Plug one cable into laptop for video, peripherals, charging, and networking. **Typical dock capabilities:** - **Video:** Dual 4K @ 60Hz (DP 1.4) or single 5K/6K display - **Data:** USB 3.2 Gen 2 ports (10 Gbps) for peripherals - **Power:** 85-100W laptop charging (TB3/TB4), up to 240W (USB-PD 3.1) - **Networking:** Gigabit Ethernet - **Audio:** 3.5mm headphone/mic jacks **Example workflow:** - MacBook Pro (Thunderbolt 4) → CalDigit TS4 dock → - Two 4K monitors via DisplayPort - USB keyboard, mouse, webcam - Gigabit Ethernet - External SSD - 98W charging **Limitations:** - **M1/M2 Macs:** Limited to two external displays (hardware limitation, not Thunderbolt) - **Windows laptops:** Some USB-C ports are USB 3.2 only—no Thunderbolt, no DisplayPort Alt Mode - **eGPU support:** Dropped by Apple on M-series chips; Windows still supports Thunderbolt eGPUs ## Common Issues ### "My USB-C Cable Won't Charge My Laptop" **Causes:** 1. Cable is USB 2.0 data-only (no power wires) 2. Charger provides insufficient wattage (e.g., 45W charger for 65W laptop) 3. Laptop requires proprietary charging protocol (rare) **Solution:** Use USB-PD certified cable rated for your laptop's wattage. ### "Monitor Not Detected Over USB-C" **Causes:** 1. USB-C port doesn't support DisplayPort Alt Mode (check for DP symbol) 2. Monitor requires Thunderbolt, but laptop only has USB 3.2 3. Cable doesn't support video (USB 2.0 or USB 3.2 Gen 1 only) **Solution:** Verify both laptop port and cable support DP Alt Mode. Use USB-C to DisplayPort/HDMI adapter if native support missing. ### "Thunderbolt Dock Only Runs One Monitor" **Causes:** 1. Laptop has Thunderbolt but only allocates DP 1.2 bandwidth (common on older laptops) 2. Dock splits DP 1.4 into two streams—each stream limited to 4K @ 30Hz unless DSC enabled 3. macOS limitation on M1/M2 (hardware display controller, not Thunderbolt issue) **Solution:** Check laptop's Thunderbolt spec. Use MST hub for Windows, accept limitations on Mac. ## Choosing the Right Cable/Dock ### For Basic Charging + Data (No Video) **USB 3.2 Gen 2 cable with USB-PD** - Speed: 10 Gbps - Power: 60-100W - Cost: $15-$25 - Example: [Anker USB-C to USB-C Cable (100W)](https://www.amazon.com/Anker-Powerline-Pull-up-Resistor-MacBook/dp/B08M647NNK) ### For Single 4K Display + Charging **USB-C to DisplayPort cable (DP Alt Mode)** - Video: 4K @ 60Hz - No dock needed - Cost: $15-$30 - Example: [Cable Matters USB-C to DisplayPort 1.4 Cable](https://www.amazon.com/Cable-Matters-DisplayPort-USB-C-Supporting/dp/B01J6DT070) ### For Dual Monitors + Peripherals + Charging **Thunderbolt 4 dock** - Two 4K @ 60Hz displays - Multiple USB-A/USB-C ports - Gigabit Ethernet - 85-100W charging - Cost: $200-$400 - Examples: - [CalDigit TS4](https://www.bhphotovideo.com/c/product/1698748-REG/caldigit_ts4_18_port_thunderbolt.html) - Premium choice, 18 ports - [Plugable TBT4-UDZ](https://www.amazon.com/Plugable-Thunderbolt-Charging-DisplayPort-Thunderbolt4/dp/B0C4RW1VR9) - Budget-friendly, solid performance ### For High-Speed Storage or eGPU **Thunderbolt 3/4 cable (active if >2m)** - Speed: 40 Gbps - PCIe tunneling - Cost: $25-$80 - Examples: - [Cable Matters Thunderbolt 4 Cable (6.6 ft)](https://www.amazon.com/Cable-Matters-Thunderbolt-Certified-Compatible/dp/B0B8X6MM2M) - Certified, affordable - [Apple Thunderbolt 4 Pro Cable (1.8m)](https://www.bhphotovideo.com/c/product/1673038-REG/apple_mwp02am_a_thunderbolt_4_pro_cable.html) - Premium active cable ### For Future-Proofing (8K, High Refresh) **Wait for Thunderbolt 5 devices (2025+)** - 80-120 Gbps bandwidth - 8K @ 120Hz support - PCIe Gen 4 - Cost: TBD (likely $400-$600 for docks) ## Summary: What You Actually Need **Check these in order:** 1. **Does your laptop USB-C port support video?** (Look for DP Alt Mode icon or Thunderbolt symbol) 2. **How many displays?** Single = simple USB-C to DP cable. Dual = need dock with TB3/TB4. 3. **Do you need eGPU or NVMe speeds?** Requires Thunderbolt, not just USB-C. 4. **How much power?** USB-PD 60W for phones, 100W for laptops, 240W for gaming laptops. 5. **Cable length?** <2m = passive TB4 cable. >2m = active cable or optical. **The golden rule:** Just because it fits (USB-C) doesn't mean it works. Always check specs.