block diagram interpretation

[Chris Murphy]

I'm looking at reducing my dependency on dual booting and VMs to run
Fedora and am thinking of an Intel NUC or possibly a Minnowboard (or
maybe both and eventually setup glusterfs).

Page 17, figure 3 show a block diagram of a candidate board
http://downloadmirror.intel.com/23090/eng/D54250WYB_D34010WYB_TechProdSpec06.pdf

What I'm wondering is, there are four USB connectors, two front, two
back. Each pair is represented with a single block with two arrows to
the CPU. Do the two arrow implies two distinct buses? i.e. each of the
four connectors offers 5Gbps bandwidth?

In contrast, there's also two USB 2.0 ports in the front, noted as
both dual-port, and with a single arrow to the CPU, which suggests to
me it's a single 480Mbps bus shared between two connectors.

Then on page 24, the text description says even less than the diagram suggests:
The board supports eight USB ports. All eight ports are high-speed,
full-speed, and
low-speed capable. The port arrangement is as follows:
• USB 3.0 ports:
 Two front panel USB 3.0 ports are implemented through an external connector
(blue)
 Two ports are implemented with vertical back panel connectors (blue)


Thanks,


-- 
Chris Murphy