[Topaz]

Having just fitted my new super slim Apple keyboard I'm surprised it won't accept my 500mb flash memory stick bought a couple of years ago. It says there is "insufficient power" to operate it. I always knew that on my old (white) keyboard it was unsuitable but I thought these new USB2 keyboards would be ok.

I have tried it on another USB connection on my Mac and it works ok on that so what's the problem?

[Cold Warrior]

Do you have a newer memory stick on hand? Technology changes fast and it's possible that a stick from two years ago draws more power than a current 2GB $25 model available anywhere. The newer ones may work with the slim keyboard.

[Topaz]

Agreed .... have just learnt from a friend ....

I'm using a 16 GB SanDisk Cruzer Micro on my aluminum keyboard right now with no problems. These things tend to become more efficient as the technology matures. Maybe yours drew too much power to begin with, or is beginning to do so because of age.

[MacNNUK]

Originally Posted by Topaz 

Having just fitted my new super slim Apple keyboard I'm surprised it won't accept my 500mb flash memory stick bought a couple of years ago. It says there is "insufficient power" to operate it. I always knew that on my old (white) keyboard it was unsuitable but I thought these new USB2 keyboards would be ok.

I have tried it on another USB connection on my Mac and it works ok on that so what's the problem?

You are quite right, the power available through a keyboard is potentially less than from a USB port on your computer.

(Although the keyboard plugs into a USB 2 port, it is only USB 1 spec dependent on model of iMac)

On my iMac from spec (possibly same for yours) (Unless it's an aluminium iMac, see further down)
Ports Two FireWire 400 ports; three USB 2.0 ports,
two USB 1.1 ports (on keyboard); VGA output(2); S-video and composite video output(2)
and
Peripheral connections
Two FireWire 400 ports; 8 watts shared
Total of five USB ports: three USB 2.0 ports (up to 480 Mbps) on computer, two USB 1.1 ports on keyboard

Don't forget the keyboard must be taking some power itself, reducing power available through it to computer USB 2 port.

My old G3 iMac used to seize up sometimes when I used a 4 way USB splitter into a USB 1 port, no problems at all with new iMac, splitter into a USB 2 port, so presumably extra power available ?

Just read Apple spec for your keyboard
http://www.apple.com/keyboard/
Two USB 2.0 ports enable you to easily connect your Mighty Mouse as well as a high-speed peripheral such as a digital camera or printer.
and
*Devices that draw high power from the USB connection, such as iPods, hard drives and some flash drives, can only be used with the new keyboard when it is attached to the aluminum iMac.

So, it was there after all ! Do you have an aluminium iMac ?

New USB flash memory is so cheap nowadays.

This may be of interest
http://en.wikipedia.org/wiki/Universal_Serial_Bus

and click on USB 2 link at bottom of page
http://en.wikipedia.org/wiki/Wireless_USB_specification

[tooki]

Originally Posted by Topaz 

I have tried it on another USB connection on my Mac and it works ok on that so what's the problem?

Old flash drives draw more power than modern ones, and the system is correctly telling you that the low-power ports on the keyboard can't run it. USB 2.0 does not increase the amount of power available.

(Apple did something special and non-standard on the aluminum USB keyboard to let it provide extra power only when connected to an aluminum iMac, which is what some of the posts above are alluding to.)

Originally Posted by Topaz 

... Maybe yours drew too much power to begin with, or is beginning to do so because of age.

The power requirements do not change with time. In fact, they're programmed into the device -- before it powers up, it must first say "Hey computer, I'm a flash drive and I need 500mA (or less, depending)." Then the computer analyzes the USB bus and if the needed power is available, it tells the device to power up. If it's not available, it tells the device "Sorry, dude" and gives you the low-power message on the screen.

[tooki]

BTW, there's no such thing as a proper USB device drawing "too much" power. The standard only allows up to 500mA of current per device. Anything outside of that is not USB-compliant, and has to be specially marked. (For instance, the SuperDrive for the MacBook Air, which won't work on any standard USB port, only on the Air.)

A USB port on a computer and on a powered hub must be able to provide the 500mA per port. Unpowered hubs (that is, ones that do not have their own power supply) can supply only small amounts of power, which is fine for devices like printers that have their own power and just need the USB for data.