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Active Thunderbolt Cables Are Hot Cables

Everything You Need To Know About Thunderbolt
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You might not think that an external connectivity solution would have thermal issues to worry about, but Thunderbolt is quite literally a hot technology.

An infrared image of where a Thunderbolt cable plugs into our motherboard reveals temperature readings above 110o F, even when downstream devices are idle. Active, we see the cable exceed 120 degrees.

Of course, those temperatures are a result of the active Thunderbolt cable, with two Gennum GN2033 chips on each end. As information moves through the cables, the hard-working data transmission chips heat up and cause those more extreme readings.

Not surprisingly, more space-constrained applications, like our 13.3" MacBook Pro, demonstrate even more alarming thermal properties. In the shot above, the Thunderbolt cable is the one up in the 120o+ range. Next to it, on the left, you can see a FireWire 800 cable. On the other side, there's a USB 2.0 cable. Although those two interfaces look like they're giving off heat as well, they're actually being warmed by the Thunderbolt cable. Fortunately, only the ends of the cable heat up; everything in between stays cool.

Those lofty temperatures aren't a problem if you're using a mini-DisplayPort adapter. The display signal is already demuxed by the controller before it hits the adapter.

So, in comparison to USB and FireWire, Thunderbolt cables get pretty darned hot. But the heat dissipated only causes the plug to become uncomfortable to handle for any significant length of time, and they won't burn you (the same conclusion we reached about gaming on an iPad 3 at maximum brightness).

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Top Comments
  • 22 Hide
    shoelessinsight , June 12, 2012 4:52 AM
    Active cables are more likely to have defects or break down over time. This, plus their high expense, is not going to go over well with most people.
  • 21 Hide
    mayankleoboy1 , June 12, 2012 4:35 AM
    thunderbolt will fail after external PCIE standard is implemented
  • 19 Hide
    Pyree , June 12, 2012 4:23 AM
    I was really hoping to see some eGPU benchmark. Oh well, I guess I have to wait.
Other Comments
  • 19 Hide
    Pyree , June 12, 2012 4:23 AM
    I was really hoping to see some eGPU benchmark. Oh well, I guess I have to wait.
  • 21 Hide
    mayankleoboy1 , June 12, 2012 4:35 AM
    thunderbolt will fail after external PCIE standard is implemented
  • 15 Hide
    mayankleoboy1 , June 12, 2012 4:36 AM
    for more insight of thunderbolt fail and Intel's lying :

    http://semiaccurate.com/2012/06/06/intel-talks-about-thunderbolt/
  • 22 Hide
    shoelessinsight , June 12, 2012 4:52 AM
    Active cables are more likely to have defects or break down over time. This, plus their high expense, is not going to go over well with most people.
  • 5 Hide
    A Bad Day , June 12, 2012 5:39 AM
    Looks like I'm going to steer clear of Copperpeak for my future build.
  • 16 Hide
    GI_JONES , June 12, 2012 5:43 AM
    Cost is going to kill this.
  • 12 Hide
    mayankleoboy1 , June 12, 2012 6:25 AM
    ^
    because "thunderbolt" sounds much sexier than "HDBaseT " ?

    and with apple, its all about the sexiness, not functionality/practicality.
  • -1 Hide
    JOSHSKORN , June 12, 2012 6:35 AM
    Prediction: We will see Thunderbolt available on SmartPhones. When we do, this port will be able to handle a monitor, external hard drives, speakers and many other USB devices through its Thunderbolt docking station. Obviously a SmartPhone won't need to be attached to a webcam. This will become the future desktop...that is, if it can run Crysis. LOL Had to add that in there. :) 
  • 3 Hide
    pepsimtl , June 12, 2012 7:02 AM
    I remenber scsi interface ,so expensive ,just the company (server) use it .
    and sata interface replace it.
    For me Thunderbolt is the same song
    I predict a sata 4 (12gb) or usb 4 ,soon
  • 13 Hide
    archange , June 12, 2012 7:21 AM
    Hot, expensive active cables cannot be anything else than niche.
  • 7 Hide
    emad_ramlawi , June 12, 2012 7:31 AM
    Technology for the rich ...

    i can wait a couple of minutes for files to be copied on USB 3.0 which is universal and open standard .

    thanks intel but ill pass
  • 4 Hide
    rex86 , June 12, 2012 7:43 AM
    I really hope that this is going to be another flop. USB3 is just fine for almost everything. I do agree that we need open external PCIe standard. We're already paying too much to Intel.
  • 6 Hide
    beetlejuicegr , June 12, 2012 9:46 AM
    Only thing usefull i can see right now is a laptop with intel/amd gpu using it to get access to high end external discrete gpu. All the other possibilities are not needed to be through thunderbolt.
  • -1 Hide
    Anonymous , June 12, 2012 10:15 AM
    What is 125oF in real measurements?
  • 0 Hide
    chesteracorgi , June 12, 2012 12:29 PM
    Thunderbolt is a wonderful innovation and alternative, but hardly ready for prime-time. Even on the Mac platform there is a derth of devices that use thunderbolt. Will thunderbolt be USB or Firewire?
  • -2 Hide
    A Bad Day , June 12, 2012 1:22 PM
    emad_ramlawiTechnology for the rich ...i can wait a couple of minutes for files to be copied on USB 3.0 which is universal and open standard . thanks intel but ill pass


    And if USB 3.0 is too slow, then use two of them (flashdrives in RAID 0 anyone?).
  • 2 Hide
    Anonymous , June 12, 2012 1:38 PM
    I can't believe how narrow some other people comments are. This new standard is for high end users and later others as well once prices start to drop. USB3 eSata when you are working with files that are 10s of Gigs in size are just too slow. Thunderbolt is fast plus easy plug and play for so many future possibilities. There are already a number of hard drives, raids arrays, Displays and now expansion Link PCIe adapter from Mlogic. Already it's potential is becoming interesting.
  • 1 Hide
    josejones , June 12, 2012 2:04 PM
    What are the costs of these new Thunderbolt ports on new z77 motherboards and are they 3rd party?

    I was considering getting the new Gigabyte Z77X-UP5 TH for my new i7 build but, not because of the Thunderbolt ports, but rather, due to the alleged lower mobo temps, which I'm concerned about with our 85F (31C) indoor temps. I await a serious review. These new boards are supposed to be available by the end of June:

    Gigabyte's Hardcore Thunderbolt Demo with GA-Z77X-UP5 TH Motherboard
    http://www.youtube.com/watch?v=deImUH8aUHQ

    Gigabyte Ultra Durable 5 at Computex, shows much lower temperatures
    http://www.youtube.com/watch?v=rLggGetNR14

    z77 Motherboard Discussion
    http://www.tomshardware.com/forum/308058-30-motherboard-discussion
  • 1 Hide
    josejones , June 12, 2012 2:17 PM
    ^ "are they 3rd party?"

    of course not = Intel
  • 1 Hide
    rantoc , June 12, 2012 2:25 PM
    I don't see this tech taking off in the consumer sector any day soon, its to expensive compared to the alternatives and with active cables it ensures that it will remain so! Few have use of the extra bandwidth provided where an usb3 will remain more than sufficient for the masses and the equipment/cables remain cheap!
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