Cheap USB hubs


DanL

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So on my iMac, I expanded my USB ports with a cheap (unpowered) USB3 hub. I've tried two different ones, in fact. I get strange performance with them. My disk backups are noticeably slower, and my mouse basically freezes about once or twice per day. The only way I can unfreeze it is by unplugging the hub and plugging it back in. Is this a well-understood situation? Am I better off with a powered hub? Are there worse and better unpowered hubs?
 
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Lufbrarunner

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I certainly get more consistent results with a powered hub. With an unpowered hub a few of my devices either worked poorly or not at all. a 7 port hub cost me around £12.
 

DanL

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Thanks. It's clear that to do charging over USB, a powered hub is absolutely essential (and that powered hub has to be plugged in to a USB port to energize it), and is also necessary for UBS-powered disks and the like. I'm just a little surprised that mice and keyboards are not necessarily happy with unpowered bugs, though I guess if that hub is sharing the minimal USB port power with a number of different low-power things, performance could suffer even for low power consumption items. I'll spring a few bucks for a powered one.
 

Cory Cooper

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Hello,

Powered USB hubs are definitely preferred over non-powered hubs. Hard drives, especially those that are bus-powered (don't have an AC adapter), require a powered hub. Also, it's best to match the USB version to the devices you attach to the hub.

-Which brand/model hub did you purchase?
-Which USB version are the devices plugged into it.

C
 

DanL

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My unpowered hubs are cheap no-name 4-port devices. I have them attached to a Dell mouse, crumb-catcher keyboard, and a mostly idle Lide 120 (USB2?) Canon scanner and LG DVD writer, and occasionally to a camera.

I long ago realized that a connection to my SATA (powered) backup disk through these unpowered hubs greatly reduces performance, so I always plug that in directly to the iMac chassis. It occurs to me that the mouse, with it's continually illuminated LED, must actually be pulling some current.

What is the power output of an iMac USB port. 500mW? Hard to believe a mouse is using more than 50mW.
 
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Cory Cooper

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You can get the current draw of the devices from System Information.

1. Click  in menu bar
2. Hold Option key down and About This Mac will change to System Information...
3. Click on System Information...
4. In the USB section, you can click on the hub and the devices to see the current draw. It will tell the the available current and the required. Since it is a non-powered hub, all the devices connected should not exceed the available current.

Yes, always plug drives directly into the Mac. Peripherals like mice and keyboards are good on hubs. Scanners and printers are dependent on brand/model.

Hope that helps narrow it down.

C
 

DanL

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OK, although the keyboard and mouse don't want to report any current draw, the other devices do.

The "available current" per Mac USB port is 1A. The scanner and DVD writer need 500ma each, presumably if running. So it would be dicey using those together on a hub connected to one Mac USB port.
 
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DanL

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Just a quick report. I now have my powered hub, and everything works marvelously. No more mouse freezes, and prompt disk backups. I'm a little surprised that even just a mouse and other presumably low powered items tax the iMac USB ports. Certainly if USB power is being used for motors (i.e. disk drives) that would be power-costly, but even for communication, things are dicey. Bottom, line - if you're having problems with connectivity of USB devices, get a powered hub.
 

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