Getting error message USB device was drawing too much power from your computer, one or more of your USB devices have been disabled. iMac

This generally means, that one of the devices you have connected to your computer, is connected to a port, or with a cable, that is not designed to carry the amount of power, this device requires.

For example, there are more than one type of USB ports, and the same goes for USB cables. Some USB ports / cables are consided 1.1 USB ports/ cables, while others are considered 2.0 USB ports / cables.

The 2.0 USB ports / cables carry more power over them than the 1.1 USB ports / cables.

If you are connecting a device, that is designed to be used with a 2.0 USB connection, and you are using a 1.1 USB port, then you may get this error

I am having the exact same problem...everything was working fine...and the only usb device I have plugged in is the keyboard. I am wondering if it has something to do with the latest Mountain Lion update...as the error message started happening the following morning. This was about 5 days ago.

I contacted apple support...they were of no help, and advised me to take my brand new (i've only had it a month) 27inch imac into the apple store for a genius bar appointment. Not convenient to say the least.

At a loss...please let me know if you find a solution.

😕

If your computer is a portable computer that depends upon a battery, then it may want you to connect your cable, so the computer has enough power for itself while charging this device.

KarenSelena wrote:

The 2.0 USB ports / cables carry more power over them than the 1.1 USB ports / cables.

That is untrue, the power spec for 1.0, 1.1 and 2.0 revisions of USB is identical.

Quote:

The USB 1.x and 2.0 specifications provide a 5 V supply on a single wire to power connected USB devices. The specification provides for no more than 5.25 V and no less than 4.75 V (5 V±5%) between the positive and negative bus power lines

The iPhone 5 ships with a 5 watt wall charger. That is what is recommended for charging the phone. The specification for USB 2, which I assume is what your computer has, is for 500ma of current at 5 volts( equal to 2.5 watts). So while it is possible to charge your phone from the USB port, it is not recommended. It will only charge at roughly half the rate it would on the wall charger and the current it wants to draw from the port is twice what the USB port will allow. As KarenSelana pointed out, if your computer is a portable plugging to power may help accomplish the task.

In both cases of the portable and the desktop, you can try resetting the SMC to try to get rid of the error.

Instructions are here

http://support.apple.com/kb/ht3964

hi,

good day

from few days ago , i recieve warning massage on my macbook air as soon as i connect any usb device such as usb flash memory as below

BECAUSE OF USB DEVICE WAS DRAWING TOO MUCH POWER FROM YOUR COMPUTER , ONE OR MORE OF YOUR USB DEVICES HAVE BEEN DISABLE.

TO PREVENT DAMAGING YOUR COMPUTER ...

kindly requested your assistance & guidance regarding above message.

thanks.

MacBook Air, Mac OS X (10.7.5), smc ver. : 1.74f4

behjou_parham wrote:

kindly requested your assistance & guidance regarding above message.

MacBook Air, Mac OS X (10.7.5), smc ver. : 1.74f4

See your other post on this issue...

https://discussions.apple.com/thread/5145583?answerId=22393415022#22393415022

The same has been happening to me... I've used the same usb port previously and I didnt have a problem with it before until a few days ago

For future people having this issue, the following worked for me:

-Unplug all USB devices from Mac

-Reset Mac

-On your iPhone, press the home button twice fast and close all open apps by swiping them upwards

-Additionally, put your iPhone on airplane mode in settings

-Now when you plug your phone in the power drain will be minimal and should charge your phone

Hope this helps