Overview of connections on the PC

If you look at the front, back, and sides of your computer, you'll see numerous connectors. Various equipment can be connected to this, but what exactly? Knowing these connections makes a purchase decision for external equipment easier, because you can be sure that it will fit. An overview of current connections.

Many ports

We used photos from two different PCs so that virtually all ports mentioned are present. Some ports are on both photos, some only on one (see the numbering).

1. USB 2.0

Every computer has them: USB ports. For many years, USB has been the standard communication port for connecting devices or transferring data. The standard has been around since 1996 and was succeeded in 2001 by the current USB2.0 protocol (480 Mbit/s). Currently USB 2.0 is reaching the limit in terms of speed. Flash memory and hard drives, for example, are much faster than the port can handle (in practice a maximum of 30 MB/s). For faster devices, firewire is sometimes used as an alternative. The successor is available in the form of USB 3.0.

2. USB 3.0

USB 3.0 is the latest version of the USB standard, which provides a solution to the speed limitation of USB 2.0. USB 3.0 offers a theoretical speed of 5 Gbit/s, which in practice (minus 'overhead') amounts to a maximum of 400 MB/s. USB 3.0 can be recognized by the blue color in the connector. The port on the computer is USB 2.0 compatible and contains additional contacts for USB3.0 speed. The cable that goes into the attached USB3.0 device is physically different. It is often still a search for a motherboard or notebook that has this port as standard (an alternative is a separate plug-in card).

3. Firewire

Firewire is an alternative standard from Apple to USB, which came on the market in 1998. Firewire is also known as IEEE 1394. It was standard on every Mac and after a few years also on PCs. In particular, in terms of speed, Firewire was technically superior to USB, so that the speed in practice was higher. The original firewire standard was succeeded a few years ago by firewire 800, which has a physically different connection. In practice, we only find firewire 400 on PCs, the connector you see in the photo. The standard is used for, for example, external hard drives and CompactFlash card readers that benefit from speed. There is also a firewire3200 protocol in the works, but does that make sense now that usb 3.0 exists?

4. Analog Audio Connections

Almost every computer or notebook has at least one 3.5mm audio jack for the speakers or headphones. Due to the rise of surround sound, we now find five or six 3.5mm sound connections on PCs. If you only use stereo speakers, you should almost always use the green connection. The blue jack is the line input, while pink is for the microphone. The other two connections are for the rear speakers, center speakers and subwoofer. However, there are no standard colors for this and the layout may vary. On notebook computers, the headphone output is sometimes combined with the microphone input or the headphone output is combined with a 3.5mm optical S/PDIF connection.


The S/PDIF is a digital audio connection that was invented by Sony and Philips (which immediately explains the first two letters). S/PDIF is available in an optical and coaxial version. The optical variant is also called Toslink (which again stands for Toshiba Link). The coaxial version uses an RCA connector, which is usually orange to avoid confusion with, for example, the same (yellow) connection for composite video. It depends, for example, on your receiver which S/PDIF connection you use. Some computers also have S/PDIF inputs.


With the Ethernet connection you connect your PC or notebook to your home network, for example via a router or modem. Although Wi-Fi is becoming more and more popular, Ethernet still offers faster and more stable transfer speeds. Modern Ethernet connections have a speed of up to 1000 Mbit/s (or 1 Gbit/s). The Ethernet connector has two status lights that indicate data activity.

7. eSATA

More and more often there is an eSATA connection on computers. It is intended for external connection of SATA drives, for example in the form of an external hard drive. The eSATA connection is a good alternative to USB 2.0 and Firewire because it offers significantly higher speeds.

8. VGA and DVI

The most commonly used connections to connect a PC to a monitor are the old-fashioned VGA connection and the DVI connection. The digital DVI port is the successor to the analog VGA port for monitors. The big difference between VGA and DVI is that VGA has some quality loss due to the conversion of a digital to analog signal. With DVI, the color information is sent directly (digitally) from the video card to the monitor. Another difference is that DVI also adds information about the resolution, so you never have to set it manually. The difference is especially visible at higher resolutions, up to a resolution of 1280 x 1024 VGA is usually quite usable.

9. HDMI and DisplayPort

HDMI and DisplayPort are also digital alternatives to the DVI connection. The main difference between HDMI and DVI is that HDMI also carries audio signals. Furthermore, the bandwidth is much larger than with DVI. An alternative to HDMI is the DisplayPort. Although the connector resembles an HDMI plug, it is not compatible. However, DisplayPort (just like HDMI) is compatible with HDCP copy protection. The bandwidth is 10.8 Gbit/s. Currently, the number of computers, graphics cards and especially monitors with DisplayPort is limited, but it is increasing. You can see the difference between HDMI and DisplayPort in the individual insert.

10. PS/2 Port

The PS/2 port is the port that was used as a connection port for the keyboard and mouse until recently. Most modern PCs use USB for input devices and sometimes even lack a PS/2 port. A purple PS/2 port is for the keyboard, a green one is for a mouse. Due to the declining popularity of the connection, we also see combo ports in some modern PCs that are suitable for both a mouse and keyboard.

New: Thunderbolt

The Thunderbolt connection is still fairly new. It's a new PCI Express and DisplayPort-based interface from Intel that is currently only found in Apple's new MacBook Pro series. Thunderbolt, previously called 'Light Peak', is an alternative to a variety of external connections such as SCSI, SATA, DisplayPort, HDMI, VGA, firewire and USB. It should ensure that the number of different ports on a computer is significantly reduced. The protocol has sufficient bandwidth to in principle replace any connection form. The current version is based on copper wire and achieves a maximum of 10 Gbit/s (twice as much as USB 3.0). Intel wants to switch to fiber in the future, making 100 Gbit/s feasible. Thunderbolt is expected to appear on PCs from other manufacturers in 2012.

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