USB Ports - Electrical Power Questions

Posted on 2014-04-16
Last Modified: 2014-05-01
I heard chatter amongst colleagues that the USB power that comes out of the rear USB ports is higher than the power emanating from the front USB ports of the PC.  is this true?  Can someone supply me with documentation of this?

Also, how much power does a USB video camera need (for lync video phone calls, one note recording, camtasia, etc.)
Question by:brothertruffle880
LVL 26

Assisted Solution

pony10us earned 167 total points
ID: 40004309
It really depends on the design of the computer.  Some reasons why it may be true:

The front ports may be USB 1.1 and the back 2.0. Common in older systems

The front ports may be split like a hub while the back ports are not.

The front ports may be (probably are) connected via wire to the MB while the rear are directly connected.

Front ports are mostly for the quick connect/disconnect of items like thumb drives while the rear are for more consistant connections like printers. It also is less likely that you will "bump" a rear connection.

There is a good wiki on USB ports:

Expert Comment

ID: 40004430
I would check with the manufacture and check the power setting on their specifications per device.
LVL 91

Assisted Solution

nobus earned 167 total points
ID: 40006019
imo it is dependent on the construction
the usb chip delivers for USB 2 0.5A at 5 V, to be deviced over all the usb ports connected to the usb hub -  you may have 2.3 or up to 6 hubs for most pc's
the front usb ports probably connect to one of the hubs (must be confirmed) - not necessary the same as the back ports - over small cable
it can be the cable is a bit too small for carrying full load for both connections

i believe this problem turns up mostly when using usb devices requiring much power; eg rotating disk drives
LVL 70

Accepted Solution

Merete earned 166 total points
ID: 40010223
Well from experience I can tell you the usb and audio are wired off from the motherboard using these tiny flat plastic splitters that fit together in a square shape so it's a nice neat fit over the circuits. Very messy if you pull them out and apart and hard to put back together when someone pulls them all out as some of these are also teh chassis fans.
I'm not electrically honed in the language just experienced it..
They connect the front and rear
Ah I found a YouTube video
How to connect front panel connectors to the motherboard

Lots of images showing what front panel connectors look like click here

If the front PC chasis panel is not included in the tower you can buy them as a separate kit

Search for>PC Chassis Front Panel

As to the power consumption? verses front and rear not true.. it depends on the device connected. HDD or headset simm card usb device printers / speakers/camera etc.
I cant answer that but refer to your motherboard manual which should have all the scemantics.
the capturing software uses your onboard PSU that is why if you plan on doing lots of video editing the video card should have 2 gigs of ram onboard and the processor 3GHz  lots of ram at least 8 gigs windows x64 power
so the power load never exceeds 65% of the max of your PSU.
Recommended Power Supply Wattage Calculator

I have always bought 850 watts Antec PSU since windows 7 maybe too much but I think it's never too much as it's the core of my computer.

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