Are the USB 3.0 ports on the newest iMacs able to run at full bandwidth independently of each other?

Each USB 3.0 port run at full bandwidth with a transmission speed of up to 5 Gbit/s. Instead of one-way communication, USB 3.0 uses two unidirectional data paths: one to receive data and the other to transmit.

Use your iMac System Information utility.

1. From the Apple  menu, choose About this Mac.
2. Click More Info.
3. Click System Report.
4. In the Hardware section of the System Report, click USB.
5. You will see the USB 3 section.
   All your USB 3 devices will appear in the "USB 3.0 SuperSpeed" section. Clicking the disclosure triangle will allow you to see more details.
   
   Ref: http://support.apple.com/kb/HT5172
   
   
   All the USB 3 hubs and USB 3 devices that conform to what is referred to as the "2008 version 1 USB 3.0 specification" are supported. The first device you plug in will configure the port, so always connect USB 3 capable hubs and/or devices first.
   
   
   
   

what needs the speed?

you'd be pretty hard pressed to find something you can connect where the usb3 even at 1/2 bandwidth would be the bottleneck

maybe a ssd ext disc

I would also like to know the answer to this specific question. Did anybody find concrete documentation regarding this specification?

Our team wanted to know if each USB 3.0 port had it's own bus able to run the theoretical 5 Gbps speed or is the theoretical speed shared between all of the ports. I ran across a post on Mac Performance Guide that spoke about the ports on the new Mac Pro (2013) that said the USB 3.0 ports share one single bus. In contrast, it states that the Retina Macbook Pros run each USB 3.0 port on independent busses, thus resulting in better performance.

So the question still stands, how does the 2012 iMac handle USB 3.0 speeds? Please provide credible documentation if you have the answer.

Thanks for any help you can provide!