The 40Gbps Mystery: USB4 vs Thunderbolt SSD Enclosures Explained (2026 Guide)
If you’ve spent any time shopping for a high-speed SSD enclosure lately, you’ve probably felt like you need a Ph.D. in electrical engineering just to understand the labels.
Both say 40Gbps. Both use the USB-C connector. Both cost a pretty penny.
So, why does one drive fly while the other crawls at half the advertised speed?
Welcome to the "Wild West" of modern data transfer. In this guide, we’re stripping away the marketing jargon to explain the real difference between USB4 and Thunderbolt enclosures, why your Mac might prefer one over the other, and how to avoid the dreaded thermal throttling.
No fluff—just the insights to help you decide without regretting that impulse buy. Let's unpack this tech tango and get you geared up.
Table of Contents
- Breaking Down the Basics: What Are USB4 and Thunderbolt?
- The Core Difference: Protocols vs. Speed
- The "Secret Sauce": Controllers Matter (ASM2464PD vs. Intel)
- Real-World Benchmarks: ZikeDrive Z666 Case Study
- Compatibility: Will it work with my iPhone 17?
- Fair Play: Other Great Options in the Market
- How to Choose the Right Enclosure for Your Setup
- FAQ: Your Burning Questions Answered
- Final Decision: USB4 or Thunderbolt?
Breaking Down the Basics: What Are USB4 and Thunderbolt?
First off, let's clear the fog: Both USB4 and Thunderbolt are like supercharged USB-C ports on steroids, but they're not twins—they're more like cousins with different gym routines.
USB4, the newer kid on the block (spec finalized in 2019 but hitting prime time in 2026 with v2), borrows heavily from Thunderbolt tech but plays nicer with budgets and devices.
It promises up to 80Gbps in v2, but real-world enclosures often cap at 40Gbps for now.
Thunderbolt, Intel's brainchild (now in version 5), is the premium option—think of it as the espresso to USB4's drip coffee.
It guarantees 40Gbps (or 80-120Gbps in TB5) with extras like daisy-chaining and rock-solid PCIe support for external GPUs or SSDs.
Why care? If you're plugging into a Mac or high-end PC, Thunderbolt feels like home turf, while USB4 shines for cross-platform warriors mixing Windows, Android, and Apple gear.
The pain point? Many folks grab a "fast" enclosure only to hit bottlenecks.
Apple's docs note that iPhones and Macs love both, but mismatched cables can turn your speed demon into a snail.
Pro tip: Always check for "PCIe tunneling"—it's the secret sauce for max SSD performance, optional in USB4 but mandatory in Thunderbolt.
The Core Difference: Protocols vs. Speed
Think of Thunderbolt 4 as an exclusive, high-end country club. It has strict rules (set by Intel), guaranteed minimums, and a heavy membership fee.
USB4, on the other hand, is like a massive public festival. It can be just as fast as the club, but because the rules are more relaxed, you might end up at a stage with bad audio if you aren't careful.
| Feature | Thunderbolt 4 | USB4 (40Gbps) |
| Max Bandwidth | 40Gbps | 40Gbps (Up to 80Gbps in v2.0) |
| Minimum PCIe Data | 32Gbps (Guaranteed) | 20Gbps to 32Gbps (Varies) |
| Compatibility | Strict (Intel-based) | Universal (Cross-platform) |
| Daisy Chaining | Yes (Standard) | Optional |
The Bottleneck: Many older Thunderbolt 3 enclosures were capped at around 2,800 MB/s because they reserved a big chunk of bandwidth for video signals, even if you weren't using a monitor!
Modern USB4 enclosures, like the ZikeDrive Z666, are smarter—they can dynamically allocate that "stolen" bandwidth back to your data.
The "Secret Sauce": Controllers Matter
If the SSD is the engine, the controller inside the enclosure is the transmission. In 2026, the battle is between two titans:
Intel JHL8440 (Thunderbolt 4): Reliable, stable, but historically capped at lower real-world speeds for storage.
ASMedia ASM2464PD (USB4): This is the "speed demon" found in the ZikeDrive. It’s the first controller to truly bridge the gap, allowing for PCIe Gen4 x4 speeds.
According to technical analysis from Tom’s Hardware, the ASM2464PD chip allows for nearly 3,800 MB/s read speeds—roughly 20% faster than traditional Thunderbolt-only enclosures.
Real-World Benchmarks: ZikeDrive Z666 Case Study
We didn’t just want to take the factory’s word for it. We put the ZikeDrive Z666 up against a standard Thunderbolt 3 enclosure using a 2TB Samsung 990 Pro SSD.
Thunderbolt 3 Enclosure: 2,750 MB/s Read | 2,300 MB/s Write
ZikeDrive Z666 (USB4 Mode): 3,763 MB/s Read | 3,180 MB/s Write
Why the difference?
The Z666 uses a high-performance aluminum heat sink design to fight the #1 enemy of speed: Heat.
Most 40Gbps drives start off fast but "throttle" (slow down) after 5 minutes of use to avoid melting.
Our testing showed the Z666 maintains 90% of its peak speed even after transferring a 1TB video project.
Compatibility: Will it work with my iPhone 17?
This is where it gets interesting. The iPhone 17 Pro and Pro Max feature a USB-C port that supports high-speed data.
While a full Z666 enclosure works brilliantly for offloading footage at the end of the day, it might be a bit bulky for "on-the-go" shooting.
For direct attachment, we recommend the ZIKE Z791C. It’s optimized for the iPhone’s power delivery limits (which are much lower than a Mac’s).
The Golden Rule: Always use a certified USB4 or Thunderbolt 4 cable.
If you use a cheap "charging cable" from a gas station, your 40Gbps drive will drop to 0.48Gbps (USB 2.0 speeds). Yes, we’ve seen it happen. It’s a tragedy.
Fair Play: Other Great Options
While we're proud of what we’ve built at ZIKE, we believe in the right tool for the right job. Here are a few other excellent enclosures worth your consideration:
OWC Express 1M2: A fanless powerhouse. It’s built like a tank and very reliable for long-term Mac Studio backups.
Acasis 40Gbps Enclosure: A great budget-friendly entry into the 40Gbps world, though it can run a bit hotter than the Z666 under sustained load.
Samsung T9 (Portable SSD): Not an enclosure (you can't swap the drive), but if you don't want to build your own, this is a solid, rugged "all-in-one" solution.
How to Choose the Right Enclosure for Your Setup
Stuck deciding? Here's your roadmap:
Budget Crunch? Go USB4—versatile for mixed devices, like backing up iPhone to Windows.
Pro Workflow? Thunderbolt for guaranteed speeds and chaining (e.g., SSD + display).
DIY Tips: Pick M.2 2280 SSDs (e.g., WD Black SN850X). Format exFAT for cross-platform. Test with Blackmagic Disk Speed Test—aim for 3,000MB/s+.
Setup Steps:
1. Slot SSD into enclosure (tool-free on most).
2. Connect via certified cable (Apple's TB cables rock).
3. Format in Disk Utility.
4. Monitor temps—add a fan if needed.
FAQ: Your Burning Questions Answered
Q: Can I use a USB4 enclosure on a Thunderbolt 3 Mac?
A: Absolutely. USB4 is backward compatible. However, you will be limited to the maximum speed the TB3 port allows (usually around 2,800 MB/s).
Q: Does the ZikeDrive Z666 need an external power supply?
A: No! It is bus-powered. However, if you are connecting it to an older laptop with a weak port, using a USB-C Hub with Power Delivery can help stability.
Q: Which SSD should I put inside my enclosure?
A: For the best results in 2026, we recommend the Samsung 990 Pro or the WD Black SN850X. They match the PCIe Gen4 capabilities of the Z666 perfectly.
Q: Which is cheaper long-term?
A: USB4—enclosures cost less, and NVMe swaps keep it future-proof.
Q: What's the real speed difference for SSDs?
A: Thunderbolt sustains higher (3,200MB/s+), USB4 varies but suffices for most.
Q: Any power draw issues?
A: Minimal—both sip from your device, but pair with powered hubs for long sessions.
Final Decision: USB4 or Thunderbolt?
In the USB4 vs Thunderbolt showdown, there's no outright winner—it's about your needs.
USB4 nails affordability and versatility for everyday hustlers, while Thunderbolt delivers pro-grade reliability for creators chasing peak performance.
Whether building with ZikeTech's Z666 or eyeing OWC's beasts, focus on solving your pains: Speed for edits, compatibility for travel.
If you want the fastest possible speeds currently available on the market and you work across both Mac and Windows, USB4 (specifically with the ASM2464PD controller) is the winner.
It breaks the "Thunderbolt Tax" and provides higher throughput for half the price.
Stop settling for "fast enough."
Get the ZikeDrive Z666 – The World's Fastest USB4 Enclosure →
Ready to upgrade? Peek our Apple accessories or Apple's guide here. Drop comments—what's your setup? Let's geek out.