Can a powered USB-hub damage my mac pro

Discussion in 'Mac Pro' started by compute, Sep 2, 2015.

  1. compute macrumors regular

    Jun 11, 2013
    Is it possible for a 4-port USB hub with power adaptor to damage my nmp? Since it's a real hassle to always turn the machine around and because there a so little USB-ports on the nmp having to remove and replace the cables i was planning on buying a USB-hub with 4 ports...

    Basically the guy at the computer store told me it was a bad idea getting a USB-hub with power because there's a big chance it could mess up my computer (current flowing backward from a malfunctioning USB-hub damaging the motherboard)

    Is all this true or was the guy full of it? I decided to ask here first before buying just in case.
  2. mikeboss macrumors 65816


    Aug 13, 2009
    unfortunately the guy is at least partly right. lots of powerd hubs are feeding current back to the host (which isn't allowed by definition). many manufacturers think they can gain higher profit by leaving out a few parts (diode). there was a test conducted by the german IT magazine c't a few months back and AFAIR two thirds of the hubs tested were feeding current back to the host. I ended up buying this industrial strength hub which cost nearly 100 bucks...
  3. flowrider macrumors 603


    Nov 23, 2012
    That's a new one on me:eek: I've been using powered hubs for quite awhile with no issues. Haven't seen any of our members have problems like the OP described.

  4. mikeboss macrumors 65816


    Aug 13, 2009
    luckily, in most cases the host's USB ports won't get damaged by the current fed to them. but it's definitely not something I'd want my USB hub doing. so I specifically bought a properly designed one.
  5. RoastingPig macrumors 68000


    Jul 23, 2012
    i had a powered usb hub powered on to a 2005 imac since 2005 and all is still working perfectly.
  6. pastrychef macrumors 601


    Sep 15, 2006
    New York City, NY
    Is it possible to protect your computer by just splicing the USB cable used to connect your Mac to the hub and cutting the VCC and Ground wires?
  7. keysofanxiety macrumors G3


    Nov 23, 2011
    I've seen USB ports on Wintels and Macs alike completely fried when using cheap USB hubs.

    OP, objectively there's no issue. Just make sure you buy a good quality one like Belkin. Don't skimp on the hub.
  8. monokakata macrumors 68000


    May 8, 2008
    Hilo, Hawai'i
    Someone I know (no, not me) reached around into a tangle of wires and accidentally plugged the wrong power plug into a powered USB hub. Bang. There went an Avid keyboard, and an Audioengine D1, and a Wacom of some kind. I think he told me that the hub was plugged into an rMBP, which wasn't harmed.

    Mind you, this was user error, but it does highlight a potential danger.
  9. haralds macrumors 6502a


    Jan 3, 2014
    Silicon Valley, CA
    For most applications, you need a powered hub. I would source from large, well known manufacturers with good reputations, who have a reputation to protect and can be sued. Avoid cheap Chinese knock offs. With proper design, there is little danger unless you plug in an incorrect power supply into the hub. And even then good design has current limiters.
  10. IowaLynn macrumors 65816


    Feb 22, 2015
    What about issues where USB devices interfere with or require you to clear NVRAM/PRAM and USB is often a factor?
  11. SoyCapitanSoyCapitan macrumors 601


    Jul 4, 2015
    I have a basic Advent powered hub. It's cheap and I hope it's safe. I only use it for the Logitech Pico adapter, Logitech webcam and Apple Keyboard.
  12. BayouTiger macrumors 6502


    Jul 24, 2008
    New Orleans
    Been using them for years on all manner of Mac and PC without issue. That said parallel DC power supplies of the same voltage are not generally going to be a problem. AC is a WHOLE other issue!
  13. h9826790, Sep 3, 2015
    Last edited: Sep 3, 2015

    h9826790 macrumors G4


    Apr 3, 2014
    Hong Kong
    Sadly it's quite common, if you touch the USB cable (of course the metal part and connected your powered hub) which suppose will plug into the Mac Pro, you may actually able to feel the electricity.

    But it cost me zero damage so far. My guess would be there is a diode inside the motherboard to stop the backward current. Since the USB port can supply power and it support hot plug / unplug. There should be a diode inside the circuit to protect the mobo. Because when you unplug a device (with positive current), there will be a huge induced backward current for a very short period of time. My understanding is that almost all circuit which able to supply power will have a diode to protect itself being fired by this backward current.

    So, I will say (in general) there is nothing to worry about. However, there is an existing small USB device that able to fire almost all circuit board by just plug into the USB port. Even that device was builded on that purpose, but it's a proof that a faulty / very poor design… USB hub may able to damage the Mac Pro.
  14. monokakata macrumors 68000


    May 8, 2008
    Hilo, Hawai'i
    I just got a response from the person who accidentally plugged in the wrong power supply to a hub. He reports that it was plugged into the rMBP at the time, but that the rMBP was unaffected -- he wrote, "just blew the hub and everything downstream."
  15. Alvinict macrumors newbie


    Dec 15, 2015
    It's very true that a powered may damage your computer logicboard. It happened to me when I was plugin in my powered USB 3.0 on the left side USB port on my MacBook Pro. Before the USB hub damaged the logic board, I realised that my left port is getting very stable if the powered USB hub is not connected. After awhile of using it it eventually killed.
  16. PowerMac G4 MDD macrumors 68000

    PowerMac G4 MDD

    Jul 13, 2014
    At the intersection of Conch and Coral.
    My 1,1 Mac Pro had an odd problem with this yeah powered hub of mine. One day, the hub stopped working completely, and El Cap was spamming me with messages about a USB device drawing too much power, and that it was going to disable said port. It ended up disabling two of my rear USB ports, and message would pop up every 5 seconds - even if no USB devices were plugged in. Wondering if it was a software issue, I tried booting into Mountain Lion. A dialogue window came up and told me about the USB port, but this only happened once; and the two ports were working just fine under Mountain Lion. I'm wondering if this is a combination of a hardware AND software issue. Either way, my 1,1 is being finicky in that regard, and my 10-port USB hub is dead.

    I've had half my USB hubs fail on me. Even the name-brand ones are just complete crap, and nobody but Chinese rip-off artists create hubs that have 10 ports and no extra frills.

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