Thread: Powering USB 2.0 Hub off HDD +5v Rail - Any problems?

if you gonna let it get power from psu .... why not buy a self powered one .... one that works off the usb 2.0 power from mobo .. (that inturn gets it from the psu ) .... so .. seems kinda useless to get it from the same source

I couldn't find one.. Can you post a link for one of these "self-powered" ones?

Anyhow, it's too late.

What I did so far was hack off the 120vAC adapter head, and wired up some terminal clips to hook into the +5v molex adapter to get power from the PSU's +5v rail. Do you think this will suffice? I don't see how it is different from using the 120vAC adapter which ouputted +5v....

Kevin

You should be fine. Just remember that each USB port on your hub is rated to 500mA by USB spec. Then add 500mA for some space. So a 4-port USB 2.0 hub needs 5V up to 2.5A regulated. Check your power-supply to make sure there's plenty available on the +5V rail.

Originally Posted by Q_gamelogic

if you gonna let it get power from psu .... why not buy a self powered one .... one that works off the usb 2.0 power from mobo .. (that inturn gets it from the psu ) .... so .. seems kinda useless to get it from the same source

i heard (dont know if its true or not) that the hub that is self powered from the mobo splits the power (500ma) between each port....

The USB port on your mobo isn't required to provide more than 500mA. So if you plug in a 5-port bus-powered hub, it has to split up this 500mA among its ports. This won't be enough if you have several high-powered devices plugged in.

You did the right thing by buying a self-powered hub and wiring it directly into your +5V rail.

Here is a really article on self-powered vs. bus-powered hubs: http://www.microsoft.com/whdc/system/bus/USB/hubs.mspx

Acctually I think Powered USB hubs can get up to 6As per port...I think the 500mA spec was on USB 1.x only. When USB 2.0 came out I think it was raised.

Originally Posted by Defiler

Acctually I think Powered USB hubs can get up to 6As per port...I think the 500mA spec was on USB 1.x only. When USB 2.0 came out I think it was raised.

According to section 7.2 of the USB 2.0 spec at http://www.usb.org/developers/docs/usb_20.zip a single USB device can consume upto 5 unit loads. A unit load is defined as 100mA.

Originally Posted by rando

According to section 7.2 of the USB 2.0 spec at http://www.usb.org/developers/docs/usb_20.zip a single USB device can consume upto 5 unit loads. A unit load is defined as 100mA.

Sorry, was thinking USB Plus power...

http://www.usbpluspower.org/

+5V @ 6A's. 6 amps down 20 Gauge USB wires.

Sounds like fun!