All PC motherboards have a rear panel (known as a back panel or I / O panel) that incorporates a multitude of connections. In this article, we are going to explain what each of these outer ports on the motherboard does, what connects to them, and why they are there.
Actually, 90% of the external connectivity of the motherboards is in this back panel, since the rest of the ports that we can find on the outside in a PC are connected to internal ports of the motherboard, that is, the motherboards too They have “ports connections” which are the cables that we connect in the box to be able to have USBs in the front, for example. In any case, this panel is there to connect all kinds of peripherals , from the keyboard and the mouse to monitor, through printers, home network and a long etcetera.
So let’s see what each of these ports does and what it is for.
The most common ports of the back panel
We are going to start looking at them from left to right and top to bottom.
- PS / 2 : this port is deprecated and fewer and fewer motherboards already have it. If you look at them, they have two colors, purple for the keyboard and green for the mouse, because in the past, before the introduction of USB, they were the colors that differentiated them, just as audio connectors still differ.
- USB 3.0: well known, they differ from USB 2.0 and 1.1 in that they are blue.
- D-SUB or VGA : is a video output for connecting a monitor.
- DVI: can be Dual Link (DVI-DL) or not. Like the previous one, it is another video output to connect the monitor.
- Optical Digital Audio Output (S / PDIF) – Used to connect digital audio systems. Unlike the minijack connection, only a single cable is required for it to work.
- HDMI : well known because it is the highest standard today, it serves as a video output to connect a monitor, but it can also be used for some audio systems.
- DisplayPort : another video output to which we can connect a monitor.
- USB 2.0 : as we have said before, unlike USB 3.0 which are blue, these are black to be able to differentiate them.
- eSATA : Some external hard drives still use this type of connector, which is nothing but “External SATA”. It is currently in disuse.
- GbE LAN : Gigabit Ethernet LAN, is linked to the network card of the motherboard, and that is where we must connect the router with an RJ-45 connector cable.
- HD Audio : Here we have either just two connectors or six, and they are used to connect analog audio devices. If there are only two, it will be green for speakers and pink for microphone. If there are six, the connection is as indicated below:
- Orange: center speaker or subwoofer.
- Black: rear speaker.
- Gray: center speaker.
- Blue: line input. It is the only connector, other than the microphone, that is an input and not an output, and is used to connect external audio sources.
- Green: front speakers.
- Pink: microphone input.
Less common ports on motherboards
On the motherboard in the image above we see three ports that we did not find before, and one more curiosity. The curiosity is that instead of having a single PS / 2 combo port for mouse and keyboard, it has them separately, green for the mouse and purple for the keyboard. As for the three ports that we didn’t see before, they’re just to the right of the PS2s, and we’re going to check them out.
- LPT (Long Purple, 25-pin): This is the famous “parallel port”, which is no longer in use. In the past it was used to connect, above all, printers and plotters, as well as some TWAIN-type scanners, and even “backpacks” with licenses to use certain licensed software.
- Serial / RS232 Port (Green, 9-pin): It is still used today in industrial and commercial environments. It is used to connect all kinds of devices, from handheld scanners to barcode readers.
- RCA Port (Orange): Oddly enough, this port is for digital audio just like S / PDIF.
Other ports that we can find on a motherboard would be the following:
- USB-C : associated with the USB 3.1 standard, instead of the usual Type-A, Type-C are gradually being implemented, but they are still the USB standard.
- Thunderbolt : also well known, and now with Thunderbolt 3 it uses a USB-C interface (previously it used a mini DP interface like the one you see in the image below). It does a bit of everything from streaming data to connecting monitors to charging devices.
- FireWire : this connector is for data transmission and has three variants (which you can see in the image below), although it is currently deprecated
