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Discussion in 'MacBook Pro' started by HiFiGuy528, Jan 14, 2010.
Which of the two USB port has full power, not shared with everything in the Mac?
The one nearest the user has power. However, on the 13" Pro the powered one also supports the SD reader. The rear has little power and supports the iSight camera.
What about on a 15 inch??
I thought they were all the same, wow.
I have never noticed any difference between the ports, I plug things in, they get power and run. When would such a difference be noticed?
Generally speaking only USB based 2.5" hard drives will notice an underpowered USB port. That's why most such drives come with a twin tailed USB cable, one for power and data and one that just draws power off a second USB port if the first doesn't have enough juice to spin the drive up.
As the poster above me states this is only noticed by devices that consume a high amount of power. The info in my first post was taken from the owner's manual.
While I have the 15" I thought both were powered. I cannot imagine apple powering one and not the other, but then stranger things have happened.
I just tried and I can spin up and use a 2.5" USB hard drive with either port. Not very scientific though.
Upon further review of my own hardcopy of the owner's manual it states "You can connect one high-powered external USB device." I take it this means both are full powered, just only one may be utilized at a time.
That would make sense, especially if the USB ports are on the same rail; if one draws current, (500 mA is common for an external 2.5" HDD) another device can't draw the same amount of current.
Woah!! This is all news to me.
I learn something new every day with these damn things.
Hmm. If the device is drawing too much power, will the computer tell you? I was recently charging a hand warmer through USB and got an unexpected error about some kind of power surge to the USB port. I wonder if that would still have happened if I used a different USB port.
That is never the case. The earlier portable external HDs included dual USB ports on one end of the cable to provide extra power, but I never used the second end. One was sufficient and this was the case with multiple computers of different age and OS. Nowadays, HD manufacturers only include a 1-1 USB cable and design those drives to be low power.
You can also find drives which come with USB cable and a power cable to be connected to mains.
"Mains" meaning an electrical outlet for those of ye who aren't British.
The worst one, which I promptly returned, was an enclosure (meant to use it with the leftover original 160GB drive) that required two USB connectors AND a mains connector. It wouldn't work otherwise.