USB drawing too much power

Hi, try resetting SMC & PRAM.
SMC -> http://support.apple.com/kb/ht1411
PRAM -> http://support.apple.com/kb/ht1379
please keep us informed...L

also, this can happen if you are using an USB hub. a USB hub only gets the power one USB device gets, and if you connect lots of the devices to it, they can draw too much power the USB hub cannot provide

I highly doubt a SMC or PRAM reset is going to help with this.

Since you seem to have multiple devices all triggering the same problem, it points to there being an issue with the USB controller on the logic board, and that of course means that you will have to get the logic board replaced.

If you can somehow narrow it down to one of those devices, then it's possible that you simply need to replace that single device.

Whatever the case, this is one more wonderful example of the craptastic USB specification. Unfortunately, the worst technology happened to win between USB and all other connection tech, and this is an example of what we get to live with as a result. Expect this problem to happen again at some point down the road, so if you don't already have the AppleCare plan, I'd pick it up if it's not already too late. It'll almost undoubtedly save you a couple hundred dollars the next time this problem crops up.

Might be a good idea to pick-up a 4 or 7 port self-powered USB hub for those devices, especially those that require charging. Not only does a self-powered hub relieve the power demand on the iMac, but it also gives a handy place to plug in multiple devices +(iPhones, iPods, Cameras, Flash Drives, iPad, etc.)+ instead of reaching around and plugging them into the back of the iMac...

Here are a few examples of some Mac compatible self-powered USB hubs

http://www.cablestogo.com/product.asp?cat_id=7035&sku=29563
http://www.provantage.com/belkin-f5u237-apl-s~7BELU034.htm
http://www.belkin.com/IWCatProductPage.process?Product_Id=198333
http://store.apple.com/us/product/TW305LL/A

And an article explaining the difference between self-powered and bus-powered hubs

http://support.apple.com/kb/TA25685

It'll be back. So it would be a good idea to see if you can pin down if it's any particular device giving you trouble. If it is one of those three devices, it'll just take out any replacement logic boards you get.

This happens when my wife or I plug in our iPhones, iPods or her iPad. We can no longer charge, update or manage these devices through our computer. Any suggestions?

Each of these devices may request more power from a USB port than the USB specs normally allow. This allows for faster charging from Macs that support this feature, but support is also dependent on which device is plugged in first.

(Refer to Powering Apple and third party peripherals through USB for more about this special feature.)

I suspect that there is actually nothing wrong with any of your Apple products & that this appears to be happening suddenly because more than one of the peripheral device's battery is discharged enough that each is requesting extra power at the same time. If you connect them one at a time until its battery is charged up enough not to ask for extra power, the warning may no longer occur & overall charge times may improve.

BTW, it is extremely unlikely that anything will be damaged by this. USB ports are well protected against over-current conditions -- that's why they shut down & generate the warning. The theory that this condition would repeatedly damage logic boards should probably be considered with a healthy dose of skepticism.

it's been happening with my lacie hd as well on both macs. i've got a imac 3.06 gb. 21.5 inch 4gb ram 2009 model with 1tb hd and dedicated graphic card and a macbook pro 13 inch 2009 model 2.56 gb 4gb ram. i constantly get the , "usb device using too much power" message and have tried it on my macbook pro with no other devices attached and as well on my imac. i even have a powered 6 port usb drive but still get this message. the lacie hd disk does work when i use it via the firewire 400/800 port but not with the attached usb chord. this has only recently stared to happen so i'm thinking it's either a glitch in SL or something's happening with my lacie portable hd (sam hecht 250 gb. portable model).
i see that this topic has been popping up on forums more recently and would appreciate help on relieving this problem.
thanks, jc