How to Install Front USB by Connecting Front USB Ports to a Motherboard?In order to have front mounted USB you must have 3 things.
- A case with USB ports in the front of it.
- A motherboard that supports front USB (usually)
- Appropriate wiring between the USB port and the motherboard
A case can support front USB in
two ways: via a pass thru connection, or via a port to header
connection. The former, pass thru connection, is compatible with all
motherboards that have USB ports.
Pass thru front USB
Pass thru front USB works by
having the ports on the front of the case connect to either a standard
USB cable, or a fairly small rounded cable. The cable goes from the
front of the case to a special slot cover with either a hole (for the
standard USB cable) or a special connector for the rounded cable. If
the pass thru USB had a standard cable, then you would simply plug the
standard cable into one of your back USB ports. If it had a rounded
cable, then you have a secondary attachment with something that looks
like an old style SCSI connector. The attachment plugs into both the
slot cover, and the back USB ports. The draw back of pass thru front
USB is that you lose the ports in the back.
Many 3rd party
devices that add front USB to a system use the pass thru system. A good
example is this now discontinued Front IO panel
Front USB via a Port to Header connection
In order to hook up a Port to
Header connection you have to make sure that the wires from your port
will connect to your motherboard's header. To do this you need to know
what header you have, and what type of connector you have on the wires.
You'll find information on both below.
Almost all motherboards these days have a USB header.
Due to size and cost restraints many motherboards only have 2 USB ports
on their back panel, but often they can actually support more then 2
USB ports. They will typically support additional ports via the use of
a USB header. A USB header is either a single or double row of header
pins on the motherboard that can be used to add additional USB ports to
a computer via the use of an appropriate set of header connectors,
wires, and a USB port. Each pin on the header corresponds to a wire
inside a USB cable. These pins must be clearly marked so that you can
hook them up to the wiring correctly. There are 2 common layouts for a
USB header.
Intel Standard USB header Layout:
(used by over 90% of motherboards)
Gigabyte Style USB header Layout:
(used most commonly on Gigabyte brand motherboards)
Now that we know the types of headers we have to take a moment to understand the USB wiring.
Understanding the wires
First off: All USB cables have 5 wires. 4 of these wires are actively used. Here's a reference from the official USB standard.
On
a front mounted USB port you'll have either the first 4 wires connected
to properly colored wires (red for power, white/orange d-, green/yellow
d+, black for ground) or all five wires attached to the port (same as
the former, but one extra black wire). Now where it gets tricky is how
to attach each of those wires to corresponding pins on the motherboard.
The
wires are "tailed" (attached to a header connector) using any one of a
number of different types of connectors. Below you'll find a list of
the common ones.
Common USB case header connectors
4 joined pins + 1 extra ground.
Compatibility: Compatible with both header arrangements because of the extra ground. May not work with some odd arrangements
To hook up carefully match each pin. For the Intel hookup you'll have
the extra ground wire not attached to anything. For the Gigabyte hookup
you'll have the extra ground hooked to ground pin on the motherboard,
and the standard ground jumper will be over the missing pin on the
header.
All pins separated
Compatibility: Compatible with every header.
If all the pins are separated the only real issue is lining up the pins
with the appropriate places on your header. It should be compatible
with all headers. Just make sure you read the writing on each
individual connector.
Please check the troubleshooting info at the end of the article for important information on this configurationPower and Ground separate, d-, d+ joined
Lian-Li styleCompatibility: Compatible with all common headers.
This sort of arrangement is common to almost all Lian-Li cases. Make
sure that you get the wires connected to your header in the proper
order. If you find that the port does not function the most common
cause is accidental reverse of the d-,d+. Try switching it.
All pins joined Intel style easy connector
making the Connection
Once you know what type of
header you have, and what type of connector you have on the wiring, you
need to connect the two of them. In order to do this, you must first
figure out what pin goes with what part of the connector. To do this,
you should first consult your motherboard manual. Below you'll find an
excerpt from a fairly recent motherboard manual for the Asus A7M266
motherboard. It's typical of a motherboard manual for a board using the
Intel standard USB header.
The
first thing you'll probably notice is that the wiring from your case
and the names of the pins might not quite match up name wise. This is a
common problem. Motherboard makers and case makers really haven't
decided on what to call each pin. Here's a rough list of names.
Power
may be called: P, VCC, USB Power, Power, and PUSB. On wiring it's
always red. Ground may be called: G, GND, Ground, and GUSB. D- may be
called: USB-, USBP-, D-, or just -. D+ may be called: USB+, USBP+, D+,
or just +.
To complicate things a bit more you'll probably
notice that there's a number before each one. Take a look at the
picture above from the USB hookup diagram for the A7M266.
You'll
see that Asus decided to number the middle pins. On the first row
(starting with pin 1, and marked with a 1) you'll find that they list
D- as USBP2-, and D+ as USBP2+. The number 2 tells you a few things.
First off: It's the 3rd USB port on the motherboard (they started
numbering at 0), second it tells you that that D- and D+ must be used
for the same port. Case manufacturers are just as likely to number
their ports differently.
Take a look once again at the 4-pin joined picture:
Notice that you're D-'s have either a 1 or a 2 on them. These also tell you that they are part of the same USB port.
(Remember, 1 port has 4 required wires). The numbering on the connector and the numbering on the header doesn't have to match.
To
connect everything grab the following connectors: a same number D pair,
(D-, D+), 1 power, and one ground. If your power and ground are
numbered make sure all 4 are the same number.
Tip: Most cases that use all separated pins will bundle these together for you to make it easier.
Now,
take your Power, D-, D+, and Ground and line the connector up with the
appropriate 4 header pins on your motherboard. The header pins will be
in a row under the Intel style, and in the Gigabyte style it will
either be a row of 1 pin, a gap, and then 3 pins, or 3 pins, a gap, and
then 1 pin. Press the connector down over the header pin and make sure
it's firmly attached. Once you have done this go back and grab another
set of connector wires (Power, D-, D+, Ground), and hook up your second
front USB port. If your case has more then 2 front USB ports, and your
motherboard has more then one front USB headers, then repeat the above
as necessary.
Example: If you were hooking up the front
USB on a A7M266, on a case with the pictured 4-pin joined connector
type then: VCC lines up with USB Power, USBP2- lines up with USB1-,
USBP2+ lines up with USB1+, and GND lines up with GND. For port 2, VCC
lines up with USB Power, USBP3- lines up with USB2-, USBP3+ lines up
with USB2+, and GND lines up with GND.
The pins on my motherboard specify positive and negative ends, but my connectors don't. How do I know which is which?
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