The CPU socket, PCIe graphics card slot, SATA and M.2 slots for hard drives, and 3pin/4pin fan connectors are familiar to everyone. However, a motherboard often has a variety of strange slots. What are they used for?
▌JFP1 (F Panel) Chassis Jumper
There is a troublesome interface that we have to refer to the manual every time we build a machine, but we have to connect it, which is the JFP1 interface (also called F Panel), which stands for Front Panel. It connects to the chassis jumper for the front panel.
It is usually located at the corner of the motherboard. If you do not connect it, you cannot power on the machine, unless some mid-to-high-end motherboards come with a separate power button. For some open test platforms, it can indeed be left unconnected. The empty space is located in the upper right corner.
Generally, the definition of FP pins is the same (Intel and other board manufacturers have defined standards), divided into 4 groups of interfaces, each group has positive and negative terminals. There is also an extra +5V power supply that is generally not used. Some brands will use text and colors to distinguish.
Of course, the real troublesome part is that the connectors provided by the chassis are often loose… very small connectors, which can be quite a pain to connect (high-end boards generally come with a hub, which is relatively better).
Generally, there is also a 4Pin interface next to the JPF interface, but it is not used for fans or RGB light strips, but is specifically for the Speaker buzzer interface.
There are 4 pins, but only two ends are effective. Some older motherboards have integrated buzzers. In ancient times, there were some drivers that could use this as a mono speaker…
Of course, higher-end boards already have a two-digit digital display (Debug Code LED), where you can see the error codes.
You can directly refer to the manual to find the problem, which is much more reliable than the buzzer. However, old motherboards rarely have built-in digital displays.
It is generally connected through PCI, PCIe, LPC interface, TPM interface (yes, that’s the Trusted Platform Module required by Windows 11), as well as different brand-specific interfaces (ASUS COM-Debug, MSI JDP, Supermicro SPI), and an external diagnostic card is used to find the problem.
If there is a problem with the overclocking settings, we need to clear the BIOS, at which point we need to use the JBAT jumper.
Shorting the two contacts can clear the CMOS (some are three pins, the third pin is not powered, with a shorting plastic cap, you pull out 1-2 pins, plug in 2-3 pins to achieve shorting), of course, removing the battery method also works (I learned this method because my dad set a BIOS password on the computer when I was young… had to learn it out of necessity).
Some boards have a dedicated CLR_CMOS_BT (Clear CMOS Bottom) BIOS clear button, with high positioning, directly built into the I/O back panel, clearing the BIOS no longer requires opening the chassis.
▌COMSerial and LPT Parallel Port
Older motherboards often have a long slot similar to the VGA interface on the back panel, which is the COM serial port (Serial), a universal interface that covers a wide range of industries. Medical devices, supermarket cash registers, engineering PLC programmers, as well as printers and older keyboards and mice all use it.
(Difference: VGA has three rows, COM has two rows)
RS-232 and RS-485 two protocols, with 9pin and 25pin types. The common D-type 9pin serial port has simplex, half-duplex, and full-duplex types, transmitting data in bit order, suitable for long-distance transmission, low cost but slow speed.
This interface is similar to the JFP front panel slot, so be careful not to connect it incorrectly. Similarly, there is also the LPT parallel port (also called J_Print) (Parallel), which is generally used for printers and comes in 25pin and 36pin types.
Both can transmit simultaneously, and are faster, suitable for short-distance devices. Generally due to their larger size, even on older motherboards, they often only provide pins.
USB2.0 and USB3.0 slots have significant size differences. USB2.0 has 5 pins on top and 4 pins on the bottom, with a notch in the lower right corner, opposite to the JFP slot.
It has a fool-proof notch at the bottom to prevent incorrect insertion. However, the USB3.0 slot is quite large, with a total of 19 pins, and its cable is hard and thick.
It is quite difficult to install and is considered one of the more poorly designed slots on motherboards… Additionally, there is an interface that looks similar to USB2.0 but is completely different in function, which is the 1394 interface. Do not connect it incorrectly.
It is used to connect a PCI expansion card that converts to IEEE 1394, a firewire interface developed by Apple, used for older video capture cards, sound cards and other multimedia hardware.
Some older DV camcorders have this interface, which can be connected to a computer to achieve video capture functionality. Nowadays, firewire devices are quite cheap, and setting up a firewire streaming device may even be cheaper than buying a USB low-quality camera… the effect might even be better.
Older motherboards also have a particularly obscure CIR infrared interface, with TX transmission (Transport) and RX reception (Receive) two interfaces.
It is considered a relatively ancient wireless transmission solution. Nowadays, most have transitioned to Bluetooth and WiFi. It can also be used to remotely control infrared devices or even create a smart home environment. (Nowadays, even if motherboards have it, they usually only have the RX receiving end, and the TX transmitting end needs to be purchased separately).
Additionally, there is a S/PDIF digital coaxial audio interface, which is rarely used. The I/O back panel usually only has 3.5mm and optical ports, while S/PDIF is often provided in pin form on the motherboard. A few motherboards will provide a 3.5mm interface on the back panel.
It is commonly found on devices like CD players, DAT, and MD players, which were jointly launched by Sony and Philips (S/P is the abbreviation of the two companies), generally, the interface on devices is RCA coaxial port or optical port, transmitting digital signals, suitable for connecting to external decoders and amplifiers, resulting in better sound quality than onboard sound cards.
Nowadays, many interfaces are fading from view. There are now interfaces and chips with higher integration, smaller size, larger bandwidth, and faster speeds, and even the power supply connectors are undergoing a transformation. Perhaps in the years to come, motherboards will present themselves in a “simpler” form, and these lesser-known interfaces will eventually become memories.
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