Thunderbolt Cable Teardown Reveals Electronics and Firmware

As noted by Arstechnica and iFixIt, Apple's new $50 Thunderbolt cable is actually a "smart" or "active" cable that contains circuitry and firmware. Arstechnica explains:

A source within the telecom industry explained to Ars that active cables are commonly used at data rates above 5Gbps. These cables contain tiny chips at either end that are calibrated to the attenuation and dispersion properties of the wire between them. Compensating for these properties "greatly improves the signal-to-noise ratio" for high-bandwidth data transmission.

iFixIt tore down the new ThunderBolt cable and found two Gennum GN2033 chips in the connector, one on each side. Additional support chips and resistors were also found for total of 12 chips and "tons" of smaller electronic components.

QBZvGuXR2nRD64NM
Gennum's chip is described as a transceiver that enables "reliable data transfer at cutting-edge speeds over low cost, thin-gauge copper cables." Early benchmarks of Thunderbolt drive enclosures show massive improvements over FireWire 800.

One interesting benefit of this "active" cabling is that current Thunderbolt ports found in the iMac and MacBook Pro will be future-compatible with planned optical Thunderbolt cables. Optical cables were part of the original plans for Thunderbolt which promises to offer much higher speeds, but the first version released are based on traditional copper wiring. Intel still plans on upgrading to optical cabling in the future, and existing Thunderbolt devices should be compatible with new cabling. This was mentioned during the original Thunderbolt roll out.

...the port you'll find in new MacBook Pros and storage devices can actually take an optical cable when those are cost-effective enough to roll out, because Intel will eventually bake the optical transceivers into the cables themselves.

Ars, however, suggests that the high cost and complexity of the cabling may be a hurdle to widespread adoption of Thunderbolt.

Popular Stories

iOS 26

When Will Apple Release iOS 26.2?

Monday December 1, 2025 4:37 pm PST by
We're getting closer to the launch of the final major iOS update of the year, with Apple set to release iOS 26.2 in December. We've had three betas so far and are expecting a fourth beta or a release candidate this week, so a launch could follow as soon as next week. Past Launch Dates Apple's past iOS x.2 updates from the last few years have all happened right around the middle of the...
maxresdefault

iPhone Fold: Launch, Pricing, and What to Expect From Apple's Foldable

Monday December 1, 2025 3:00 am PST by
Apple is expected to launch a new foldable iPhone next year, based on multiple rumors and credible sources. The long-awaited device has been rumored for years now, but signs increasingly suggest that 2026 could indeed be the year that Apple releases its first foldable device. Subscribe to the MacRumors YouTube channel for more videos. Below, we've collated an updated set of key details that ...
Sad Siri Feature

Apple AI Chief John Giannandrea Retiring After Siri Delays

Monday December 1, 2025 2:16 pm PST by
Apple AI chief John Giannandrea is stepping down from his position and retiring in spring 2026, Apple announced today. Giannandrea will serve as an advisor between now and 2026, with former Microsoft AI researcher Amar Subramanya set to take over as vice president of AI. Subramanya will report to Apple engineering chief Craig Federighi, and will lead Apple Foundation Models, ML research, and ...
Netflix Smaller 4

Netflix Kills Casting From Its Mobile App to Most Modern TVs

Monday December 1, 2025 4:36 am PST by
Netflix has quietly removed the ability to cast content from its mobile apps to most modern TVs and streaming devices, including newer Chromecast models and the Google TV Streamer. The change was first spotted by users on Reddit and confirmed in an updated Netflix support page (via Android Authority), which now states that the streaming service no longer supports casting from mobile devices...
ios 18 to ios 26 upgrade

Apple Pushes iPhone Users Still on iOS 18 to Upgrade to iOS 26

Tuesday December 2, 2025 11:09 am PST by
Apple is encouraging iPhone users who are still running iOS 18 to upgrade to iOS 26 by making the iOS 26 software upgrade option more prominent. Since iOS 26 launched in September, it has been displayed as an optional upgrade at the bottom of the Software Update interface in the Settings app. iOS 18 has been the default operating system option, and users running iOS 18 have seen iOS 18...
Touchscreen MacBook Feature

Here Are the Four MacBooks Apple Is Expected to Launch Next Year

Monday December 1, 2025 5:00 am PST by
2026 could be a bumper year for Apple's Mac lineup, with the company expected to announce as many as four separate MacBook launches. Rumors suggest Apple will court both ends of the consumer spectrum, with more affordable options for students and feature-rich premium lines for users that seek the highest specifications from a laptop. Below is a breakdown of what we're expecting over the next ...
iphone 17 cyber

iPhone 17 Demand Is Breaking Apple's Sales Records

Tuesday December 2, 2025 9:44 am PST by
Apple's iPhone 17 lineup is selling well enough that Apple is on track to ship more than 247.4 million total iPhones in 2025, according to a new report from IDC. Total 2025 shipments are forecast to grow 6.1 percent year over year due to iPhone 17 demand and increased sales in China, a major market for Apple. Overall worldwide smartphone shipments across Android and iOS are forecast to...
Cyber Week Deals 2025

Best Cyber Week Apple Deals Include Big Discounts on AirPods, Apple Watch, and More

Sunday November 30, 2025 7:33 am PST by
Cyber Week is here, and you can find popular Apple products like AirPods, iPad, Apple Watch, and more at all-time low prices. In this article, the majority of the discounts will be found on Amazon. Note: MacRumors is an affiliate partner with some of these vendors. When you click a link and make a purchase, we may receive a small payment, which helps us keep the site running. Specifically,...
iOS 26

What to Expect From Apple This December: iOS 26.3 Beta, Replay 2025, and More

Monday December 1, 2025 8:40 am PST by
The calendar has turned to December, and the quieter year-end holiday season is now upon us. Nevertheless, we can still expect a few things from Apple this month. Apple previously announced that iOS 26.2 will be released to the general public in December, and we can expect corresponding updates to be released as well, including iPadOS 26.2, macOS 26.2, watchOS 26.2, tvOS 26.2, and visionOS...
studio display purple february

M5 iPad Pro Could Hint at New Studio Display Feature

Sunday November 30, 2025 10:30 am PST by
The updated specs of the M5 iPad Pro may point toward a major new feature for Apple's next-generation Studio Display expected in early 2026. Apple's latest iPad Pro debuted last month and contains one display-related change that stands out: it can now drive external monitors at up to 120Hz with Adaptive Sync. The feature should deliver lower latency, smoother motion, and fewer visual...

Top Rated Comments

cmaier Avatar
188 months ago
Yeah, I don't think Monoprice is going to sell these things for $8 like everyone expected.
Score: 47 Votes (Like | Disagree)
RoelJuun Avatar
188 months ago
And still everybody keeps telling that Apple isn't interested in de Pro market and thinks only of the consumers ;)
Score: 18 Votes (Like | Disagree)
mrfoof82 Avatar
188 months ago
Not entirely surprising.

Keep in mind, Thunderbolt is two 10Gbps channels. Let's face it -- 20Gbps aggregate bandwidth is a LOT of bandwidth for an external cable which is getting up there in numbers to rival the amount of memory bandwidth most commodity computer chipsets have (I think two-channel X68 is 21.6Gbps), and those chipsets aren't exactly dirt cheap. This is bandwidth normally the realm of single mode fiber optics for cabling, and even then, the equipment on either side of that single mode cable isn't cheap.

This is not a dumb piece of shielded wire. This is a PCI-E breakout.

This is why the first thunderbolt peripherals are DAS RAID arrays and FCAL HBAs. This is stuff really intended for the professional market at the moment, not consumer devices, as there isn't a consumer device need for this crazy (yes, it's crazy!) amount of bandwidth. Not until production significantly catches up will things start to become cheap enough to make consumer devices.

This is why Apple is pushing Thunderbolt. Even in it's first incarnation it is an insane amount of overkill. It will not be quickly obsolesced.
Score: 17 Votes (Like | Disagree)
Justinf79 Avatar
188 months ago
And that's why they're $50. :)
Score: 14 Votes (Like | Disagree)
Eduardo1971 Avatar
188 months ago
Wow; is this the first time that iFix it has torn down a cable?

Too funny.:)
Score: 14 Votes (Like | Disagree)
elithrar Avatar
188 months ago
Why couldn't apple just put those chips in the computer themselves.
My gut feeling was so they have an excuse to charge an arm and a leg for the cables.

Because the chips help with handling attenuation on the cable, and it's part of the Thunderbolt spec. Without the chips, reaching 20Gbps over copper is incredibly hard.

PS: Read http://news.ycombinator.com/item?id=2711918 for a better understanding.
Score: 9 Votes (Like | Disagree)