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2009년 중반기 모델 A1278 / 2.26 or 2.53 GHz Core 2 Duo 프로세서 EMC 2326

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USB Port power rating

I have just installed a 512gb hard drive and was going to transfer data from the old hard drive to the new one. When I connected (this was after installing Yosimite OS) the usb cable to the port a message came up saying 'unable too much power required'. I am using a UB30 unit. The question is - is this Macbook usb port only capable of a 2.0

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John Scott, just as a comment and most likely more for informational purpose (since it will not resolve your question.) USB 3.0 supports high data transfer speeds of up to 5Gb/s and is also capable of maintaining currents and voltages up to 900mA at 5V for a maximum power output of 4.5W.

If I am remembering correctly these only have 1 usb port capable of powering and or charging something. The others are for data transfer only. USB 3 is backward compatible with USB 2. The USB 2 specifications call for 5VDC, with no amperage requirments.

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Use this cable with two USB connectors. Some externals HDs need more power to function properly.

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Historically on Macs the port closest to the Mag_safe port provides more power. Plug the Mag-Safe in when using externals or installing software. The cable lemurs suggested will also help. Having a charged up battery will also help.

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