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Learn to identify common ATX motherboard components

Can you tell from a glance if a motherboard has on-board sound and video? Do you know which expansion slots are brown and which are white? If not, it might be time for a little refresher course on ATX motherboard basics.


Unless you frequently handle PC hardware, finding your way around a motherboard's plastic slots and silicon chips can be a bit confusing for the novice tech or even the seasoned IT pro.

Although different motherboard designs abound, all ATX form factor motherboards have common components that you should recognize. You may already be able to identify some components, such as the PCI slots or CPU interface. But can you tell the difference between a motherboard with on-board sound and one without?

While this is not a complete description of every resister and capacitor, the following article will help you to more quickly distinguish common ATX motherboard components, such as the IDE and floppy drive controllers, on-board sound and video chips, expansion slots, and RAM memory slots.

ATX form factor basics

Figure A: Slot 1 and Socket 370 ATX motherboards


Figure A shows two ATX form factor motherboards. Although the boards are configured for different CPU types, they do have many similar features. The expansion slots are located on the end of the board opposite the CPU. The I/O ports are stacked behind the CPU, and the memory slots are in front of the CPU. All ATX motherboards also use the same colors for denoting the different types of expansion slots. ISA slots are black, PCI slots are white or beige, and the AGP slots are brown.

Figure B


When installed in the PC case, the power-supply cooling fan is also placed to blow directly on the CPU. This greatly aids in cooling the CPU and other internal components. (See Figure B.)

On-board sound and video

Figure C


Many ATX motherboards have built-in sound, video, and network adapters. Figure C shows built-in sound and AGP video chips. Although several manufacturers make these chips, most are clearly marked for easy identification.

Some boards not only have built-in video but also an AGP slot that allows the addition of a separate video card. The same option is available for upgrading sound, but a PCI or ISA slot would be used to install a separate sound card.

Floppy and IDE controllers

Figure D


Most modern motherboards have one floppy drive controller with a 34-pin male jack, as shown in Figure D.

Figure E


The IDE drive controllers are similar to floppy controllers but have either 39 or 40 pins, and there are normally two of them, as shown in Figure E.

RAM memory
Modern ATX motherboards use either 168-pin DIMM or 184-pin RIMM RAM chips. They are not interchangeable. Figure F shows three slots for 168-pin DIMMs, and Figure G shows four slots for 184-pin RIMMs.

Figure F


Figure G


Want more?
For more memory information, check out Kyu Rhee's article "Quickly identify RAM chips with these tips."

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