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Problems with USB ports having not enough energy...

majordude

majordude

macrumors 68020
Original poster
Apr 28, 2007
2,441
75
Hootersville
I have an early 2007, top of the line 17" MBP. About a year ago I noticed that some USB drives didn't like the right side of my computer. Now modern drives (like a Seagate 1TB GoFlex USB 2.0/3.0) won't load on the left side after boot or disappears after loading after boot (several hours later).

If I connect a Staples POWERED USB hub and connect these drives everything works (so far).

Can anyone shed any light on the situation? :confused:
 
"Errr, yeah. But WHY?"

Mac USB ports do not supply as much power to external devices as do PC USB ports.

For some reason, when Apple implemented their designs for USB, the "specs" called for less power.

There _are_ a few exceptions. I believe the USB port on the [older] single-port MacBook Air models supplied power equal to that of most PC's. I think there is at least one "higher-power port" on the current MacBook Air models, and possibly on some MacBook Pro's as well.

I have an external portable Firewire/USB enclosure that will run fine when connected via firewire (Mac firewire ports supply higher power than the USB ports). But it _won't_ connect when I try to run it from a single USB cable. I have a second "double-headed" USB Y-cable that it can connect with.

The solution is easy -- as you have discovered, use a powered USB hub to provide the necessary power. Then everything works, although it's one more thing to have attached to the Mac....
 
Fishrrman said:
"Errr, yeah. But WHY?"

Mac USB ports do not supply as much power to external devices as do PC USB ports.
Click to expand...

This is not correct in my experience. If you take a Macbook Pro 2007 you can charge an iPad on it. Now take a PC from 2007 and you will have problems most likely.

When the iPad came out everyone at work was getting them and trying to hook them to their work laptops to charge them, then would put in an IT work order (which came to my department) because their iPads won't charge :/

In my experience the Apple USB ports provide more power and I've always been able to run anything off of them. (My USB powered Christmas lights run brighter on my mac than my PC.)

Of course it all depends on brand two, some notebooks are better than others.

OP you may want to try switching cables, believe it or not those cables go bad often. I have a drawer full at work and out of 50+ cables around 11 are bad. If its not the cable your ports may be going bad : /
 
 
Last edited:
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