1.    11 Aug 2016 #1

    Powered USB HDD - vs Self powered USB -- load on computer ?

    Hi there

    Intuitively one might think using Powered (from the mains) external USB HDD's would require more power from the computer as well compared with those small self powered units.

    I've no way to measure this but I'm sure the small units might consume MORE power as the computer has to supply all the power for Disk rotation and the USB I/O controller.

    I only ask this because I need to put two large powered USB units (both with 2 X 3 TB Raid 0 HDD's in each unit) on to a USB 3 Hub.
    The two HDD units seem to perform perfectly well whether connected to the chargeable port on an HP laptop or the "non chargeable" ones.

    The RAID 0 is powered by the HDD itself (internal Hardware RAID) --used RAID 0 for speed -- don't need to mirror etc - I've enough backup if the whole thing goes bonkers. !!

    The files on these HDD's are serving music and video so not intensive used -- don't seem to have any problem streaming media from the laptop.

    Any engineers out there - curious over what is the actual load (power wise) on the computer if a POWERED USB HDD is used compared to a Self powered one. Note the Hub I'm using is not also powered.

      My System SpecsSystem Spec

  2.    15 Aug 2016 #2
    Join Date : Aug 2016
    Posts : 4
    Windows 10 Pro

    We can suppose that a portable HD enclosure that has it's own power supply doesn't draw as much current from the 5 volt supply provided by the USB bus.

    On a purely practical basis it simply doesn't matter. There are hard limits to how much current a USB port will deliver. USB 2 ports are limited to 500 mA, which is why they can be so bad for charging smart phones & tablets. A USB 3 port supports up to 900 mA.

    The load presented to the host is not relevant. The external device either works or doesn't.
      My System SpecsSystem Spec

  3.    15 Aug 2016 #3
    Join Date : Dec 2013
    Sydney, Nova Scotia, Canada
    Posts : 7,617
    Windows 10 IoT

    How much power they need depends on the drive(s) in the enclosure. A full size spinner will need a lot more juice than a say a smaller laptop drive. An SSD will need even less power. A 10,000 RPM drive will draw more current than 7200 RPM drive, and 7200 RPM drive more than 5400 RPM drive. In most cases. More platters means bigger motor etc. Lots a variables. As mentioned above USB ports are current limited and will just shut down when overloaded. A self powered enclosure likely draws no power from the PC, Data only.

    I made my own custom USB cables for my Raspberry PI SBC. It is limited in how much current it can supply via the USB ports. It can't do the 500ma per port. I connect Data only from The Pi's USB port to the USB device. Power to the device comes directly from a 10 A 5V power pack, that also powers the Pi. No power drops or overloading the PI's USB ports. It basically does what those externally powered enclosures do. No load on the USB port.
      My System SpecsSystem Spec


Similar Threads
Thread Forum
Started telling me I had spyware so I powered off my PC confused,help?
So like I said I obviously have a virus it started telling me that. I powered off my PC and when I tried to log back on it said something about an invalid handle.
AntiVirus, Firewalls and System Security
Solved win 10 PC will not find my USB powered external HDD.
:( G'day to all, I recently bought a new PC with win 10 on board. I now find that I want to retrieve some data from my old PC which is unserviceable. I purchased a 22 pin sata to usb cable. When plugged in I find the Device manager will not find...
Drivers and Hardware
Solved New mobo shutting down leaves usbs powered
So I got a new asus M5a97 for a new socket and whatnot and now when I shut down there are 2 issues (title bar not long enough for both) The first is whenever you shut it down it leaves all usb ports powered. The second is that every second time...
Drivers and Hardware
Office Office Clip Art now powered by Bing Images
Windows 10 News
Bay Trail-powered USB Stick launched
This sounds very tempting but maybe too late for me since I already have a Win 8.1 tablet with Intel Bay Trail CPU (ASUS T-100). Intel launches Bay Trail-powered USB stick which is capable of running 32-bit Windows 8.1 Read more here.
Chillout Room
Our Sites
Site Links
About Us
Windows 10 Forums is an independent web site and has not been authorized, sponsored, or otherwise approved by Microsoft Corporation. "Windows 10" and related materials are trademarks of Microsoft Corp.

© Designer Media Ltd
All times are GMT -5. The time now is 03:27.
Find Us
Twitter Facebook Google+

Windows 10 Forums