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[ The PC Guide | Procedure Guide | Physical Installation Procedures ]

I/O Port Connector Physical Installation Procedure

This procedure describes how to install serial and parallel port connectors to the system case of a system that uses the AT form factor, and connect them to the motherboard. These are the 9-pin or 25-pin connectors on the back of the system case into which you plug the cables for your printer, modem, or other peripherals. You will generally use this procedure when installing a new motherboard or building a new system. ATX form factor motherboards have these connectors integrated onto the board and therefore do not require this procedure.

Procedure Overview:

  • Difficulty Level: 2 (Low).
  • Risk Factor: 2 (Low). There is a slight risk of damaging the port connectors, but it's slight, and the components are not valuable.
  • Hardware Required: Depends on how exactly you install the ports, but you may need one or more of the following:
    • Phillips head screwdriver, if you are going to install the ports into an expansion card slot insert.
    • Either a 3/16" hexagonal nut driver, or a pair of pliers, if you plan to mount the ports directly into the system case. I strongly recommend the 3/16" nut driver for this procedure, as it will save you a lot of time and hassle.
  • Software Required: None.
  • Time to Perform: 5-10 minutes.
  • Preparation / Warnings:
    • If you have not already done so, please read the section on general installation and assembly tips.
    • You should have the motherboard already installed in the case before commencing.
    • The standard for I/O port connectors is one parallel port and two serial ports, and this is what this procedure assumes.
    • Be very careful when tightening the hexagonal nuts on the port connectors. If you use too much force the nut will shear right off from the threaded screw portion and ruin the connector. When tightening with a nut driver, the sensation can change from "this feels too loose" to snap rather quickly. (You can guess how I know this. :^) )
    • Make sure that you install the I/O ports that come with the motherboard being used in the system. These ports are not universal and you may have problems if you use a type that was not specifically matched to your motherboard.
    • I assume that the I/O port connectors came pre-mounted into screw-in expansion slot inserts, as they do with most motherboards.

Procedure Steps:

  1. Determine Install Method: There are two distinctly different ways to install the I/O connectors. The I/O connectors are normally pre-mounted into slot inserts that are meant to be placed into expansion slot bays in the back of the PC. You can insert them there if you wish. The main advantage of doing this is that it saves time and hassle. There are disadvantages however: you will end up blocking off one or more of your motherboard expansion slots; the connectors will tend to be less rigid and harder to attach cables to when installed this way (because the metal slot insert will bend when pressure is put on it); and the cables inside the box coming from the connectors will get in the way of other parts of the motherboard more. The alternative is to remove the connectors from the metal inserts they come in, and mount them directly to the system case. This takes more work.

Note: Depending on your hardware, you may have no choice about how to do the installation. If your connectors did not come preinstalled in metal slide-in expansion card inserts, you will have to use the mounting holes in your case. On the other hand, some system cases may not have direct-mounting holes, so you will have to use the inserts in this situation. Also watch out for a mismatch in size on the second serial port connector: some motherboards ship with two 9-pin serial connectors while some cases have holes for one 9-pin and one 25-pin, and vice-versa. If you have a mismatch here, again, you may need to stick with the inserts.

If you are going to leave the connectors in the metal inserts, continue with these steps:

  1. Identify Slots for Installation: Choose an appropriate location for the inserts; you will usually need two of them. The best expansion slots to choose are any that don't actually line up with expansion slots on the motherboard (most systems have more inserts in the case than the motherboard actually has slots). This way you don't unnecessarily block off any expansion slots on the motherboard. You will also generally want to use slots near where the port cables connect physically to the motherboard; make sure the cables will reach.
  2. Remove Slot Inserts: If there are any blanks in the slots you want to use, remove them using a screwdriver. Save them in case you ever need them again in the future.
  3. Install Port Connector Inserts: Mount the connector port inserts into place and secure them using a screw for each.
  4. Double-Check Installation: Check to make sure the connectors are installed properly. They should be secure in their installed location. Try attaching an external cable to one of the connectors if you wish, to verify that it works.
  5. Connect Cables to Motherboard: Connect the internal cables coming from each connector to the appropriate headers on the motherboard. Refer to your motherboard manual if you need it. Be sure to line up the red wire on the cable with pin 1 on the connector. If you have one 9-pin serial port connector and one 25-pin, you will normally want to make the 9-pin the first serial port and the 25-pin the second.

If you decide to mount the connectors directly to the system case, continue here instead:

  1. Identify Mounting Holes: Many cases, especially larger ones, come with many holes, more than you need to mount your connectors. Choose three holes that are the right shape to match the size of connectors you have (9-pin or 25-pin). Try to keep the serial ports together and the parallel port separate if possible, as this makes things less confusing for some users. Make sure that the cables coming from the connectors are long enough to reach the motherboard headers to which they will attach, from the location you are selecting.
  2. Open Mounting Holes: Remove any metal plates blocking off the mounting holes. These are usually either held in place with screws on older cases; on newer ones the manufacturer just punches the outline of the hole and leaves the metal part connected to the case with a sliver of metal. For these, punch the metal out using a screwdriver, or bend the metal back and forth until it snaps out of the way.
  3. Remove Connectors From Metal Inserts: Unscrew the connectors from the metal inserts they come in. Use a nut driver (if you have one) or a pair of pliers. Quick tip: to remove a connector you don't have to completely remove both screws. Remove one and loosen the other half-way, and the connector will slide out. Doing this saves time and makes mounting the connectors into the case easier.
  4. Mount Connectors to System Case: Slide the connectors into the holes in the back of the case and then tighten the hexagonal nuts using either a nut driver or a pair of pliers. Don't leave them too loose, or they will come off when you detach a cable weeks or months later. Don't over-tighten them, or they will snap off and leave you with a mess to deal with. Also, be careful not to mount the connectors upside-down; the longer side should be up (the row of 13 pins on a 25-pin connector, or 5 pins on a 9-pin connector) and the shorter side down (the row of 12 or 4 pins).
  5. Double-Check Installation: Check to make sure the connectors are installed properly. They should be very secure in their location in the back of the case. Try attaching an external cable to one of the connectors if you wish, to verify that it works.
  6. Connect Cables to Motherboard: Connect the internal cables coming from each connector to the appropriate headers on the motherboard. Refer to your motherboard manual if you need it. Be sure to line up the red wire on the cable with pin 1 on the connector. If you have one 9-pin serial port connector and one 25-pin, you will normally want to make the 9-pin the first serial port and the 25-pin the second.

Next: PS/2 Mouse Port Connector Physical Installation Procedure


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