ISC101.2-1-06-Motherboard.Pdf

Here you can see an annotated photo of a motherboard. It dates from 2007, so some of its components and connectors are a little outdated, but most of them stay the same in nowadays personal computers. In a modern personal computer motherboard we have: Power connectors to get electrical power from the power supply A socket to install a CPU. In some cases the CPU is directly soldered to the computer Slots to install the system’s main memory A chipset which interfaces the CPU with the main memory and the peripheral buses Non-volatile memory chips containing the system’s firmware needed to load the operating system from the hard disk (known as BIOS for Basic Input/output System) A CMOS memory chip and its battery A clock generator which produces the system’s clock signal to synchronize the various components Slots for expansion cards, that give access to the peripheral bus managed by the chipset An integrated controller for permanent storage devices, typically a SATA bus driver, and its connectors An integrated controller for keyboard and mouse. In legacy computers we will find also a serial and parallel port. All of them have been substituted by USB bus. One or several integrated USB bus controllers to connect external peripherals. The current USB standard is 3.1 Heat sinks and mounting points for fans to dissipate excess heat In modern motherboards a lot of functions that were initially provided with expansion cards are now integrated, so we can find a graphics controller, a sound card and a gigabit ethernet network controller and their connectors. One of the most visible points in a motheboard is the expansion slots area . Expansion slots are connectors where expansion cards can be connected. The most usual expansion cards used to be sound cards, network cards and graphics cards. As more and more functions have been incorporated in the motherboard the importance of expansion slots has diminished, so in newer motherboards you will find less than in older ones. The first expansion slot technology in PC cards was ISA, then PCI was introduced and later it evolved into PCIexpress or PCIe. In nowadays motherboards you usually find PCIe slots and some PCI ones for legacy expansion cards. You will also find a higher bandwidth PCIe slot to connect an external graphics card in case you need more graphics performance than the one you get with the integrated graphics card. For main memory, personal computers use a type of RAM called Dynamic RAM or DRAM. It is packed in memory modules called DIMM (for dual in-line memory module) and a motherboard usually has several slots to add them. The memory capacity of DIMM modules currently installed in personal computers goes from 1 to 16 gigabytes. DIMM modules use a technology called Dual Data Rate (DDR) that is able to exchange data twice per DRAM clock cycle. The most recent version of DDR is DDR-4. Many motherboards have dual-channel-enabled memory controllers that use separate channels to communicate the memory with the CPU, what theoretically multiplies the data rate exchange by two. In these motherboards memory layouts typically have color-coded DIMM sockets. A chipset is one or several integrated circuits that manage the interface between the CPU’s and the main memory and peripherals. It used to be made of two chips known as "northbridge" and "southbridge”. The northbridge links the CPU to very high- speed devices, especially RAM and graphic controllers, and the southbridge connects to lower-speed peripheral buses as harddisk and USB buses. The northbridge connects directly to the CPU using an interface traditionally known as front side bus (FSB) and the southbridge connects to the northbridge. In many modern chipsets, the northbridge has been integrated in the processor chip and the southbridge contains some on-chip integrated peripherals, such as Ethernet, USB, and audio devices. .

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