PC Hardware A Beginner's Guide

IBM created the de facto PC standard (and trademarked the name) when it shipped the first IBM Personal Computer in 1981. For more than five years, until its introduction of the ill-fated proprietary PS/2 line in 1987, IBM defined the PC standard. But the days when any PC maker defined the PC standard are far in the past. These days, Intel and Microsoft jointly define the de facto PC standard. In fact, a good working definition of a PC is a computer that uses an Intel or compatible processor and can run a Microsoft operating system. Your computer has about a dozen components you need to consider, including the processor, memory,  power supply, case, hard disk, optical drive, display, network, modem, sound, and printer. (Don’t panic i will explain what each of those is.).  One of the great strengths of the PC architecture is that it is extensible, allowing a great variety of components to be added, thereby permitting the PC to perform functions its designers may never have envisioned. However, most PCs include a more-or-less standard set of components, including the following:




Motherboard
The motherboard, is the heart of a PC (Personal Computer). It serves as "Command Central" to coordinate the activities of the system. Virtually every internal component in a PC connects to the motherboard, and its features largely determine what your computer is capable of, not to mention its overall performance.  Several common form factors are used for PC motherboards. The form factor refers to the physical dimensions (size and shape) as well as certain connector, screw hole, and other positions that dictate into which type of case the board will fit.


The more commonly known PC motherboard form factors include the following:

Obsolete Form Factors

• Baby-AT (PC and XT)
• Full-size AT
• LPX (semiproprietary)
• NLX
• WTX
• BTX, microBTX, picoBTX


Modern Form Factors

• ATX and variants; microATX, FlexATX
• DTX/Mini-DTX
• ITX/Mini-ITX


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Motherboards includes the following components:


Chipset
The chipset provides the intelligence of the motherboard, and determines which processors, memory, and other components the motherboard can use. Most chipsets are divided physically and logically into two components. As a rule, the chipset consists of two units, the Northbridge and the Southbridge. The reason that it is made of two units instead of one is that it's difficult to integrate all components onto a single chip.   A northbridge or host bridge is a microchip on some PC motherboards that is connected directly to the CPU (unlike the southbridge) and thus responsible for tasks that require the highest performance. The northbridge typically handles communications among the CPU, in some cases RAM, and PCI Express (or AGP) video cards, and the southbridge.   For Intel Sandy Bridge and AMD Accelerated Processing Unit processors introduced in 2011, all of the functions of the northbridge reside on the CPU,  while some high-performance CPUs still (2013) require northbridge and southbridge chips. The Southbridge manages the USB, audio, ISA bus, bridges the PCI and ISA busses, and incorporates a Super I/O controller, which provides serial and parallel ports, the IDE interface, and other I/O functions. In systems with Intel chipsets, the southbridge is named I/O Controller Hub (ICH), while AMD has named its southbridge Fusion Controller Hub (FCH) since the introduction of its Fusion APUs. Some recent chipsets, notably models from Intel, no longer use the old Northbridge/Southbridge terminology, although the functionality and division of tasks is similar. Beginning in 1999, chipsets from Intel began using hub architectures in which the former North Bridge chip is now called a Memory Controller Hub (MCH) or an I/O Hub (IOH) and the former South Bridge is called an I/O Controller Hub (ICH). Other recent chipsets put all functions on one physical chip.

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CPU slot(s) and/or Socket(s)

The type of CPU slot or socket determines which processors the motherboard can use. The CPU is installed in either a socket or a slot, depending on the type of chip. One key innovation was to use a zero insertion force (ZIF) socket design, which meant that you could easily install or remove the processor with no tools. ZIF sockets use a lever to engage or release the grip on the chip, and with the lever released, the chip can be easily inserted or removed. The ZIF sockets were given a designation that was usually imprinted or embossed on the socket indicating what type it was. Different socket types accepted different families of processors. If you know the type of socket or slot on your motherboard, you essentially know which types of processors are designed to plug in. Some motherboards have two or more CPU connectors, allowing them to support multiple processors.
CPU Socket Specifications

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Voltage Regulator Module (VRM)
VRMs supply clean, tightly regulated voltage to the CPU. Faster CPUs draw more current. Good VRMs are expensive, so some motherboard makers use the lowest-rated VRM suitable for the fastest CPU the motherboard is designed to support. Better VRMs allow a motherboard to accept faster future CPUs with only a BIOS upgrade.








Expansion Bus Slots
An expansion slot is a socket on the motherboard where expansion cards can be plugged into. An expansion card, also referred to as "expansion boards," "controller cards," or "adapters," is a small circuit board that enhances the functionality of a computer by enabling a computer to control storage devices, input devices, or output devices. Examples of expansion cards include graphics cards (or video cards) and sound cards.  The type and number of expansion bus slots determine the type and number of expansion cards you can add to the system. Recent motherboards may have PCI expansion slots and VGA slot, although many recent models have only PCI-E  slots. Current systems offer one to five or more PCI and PCI Express slots (depending on the form factor). Some boards have more than one PCIe x16 (video card) slot, which you may want if you are running multiple video cards in an SLI or CrossfireX arrangement. Typically, a notebook computer is equipped with PCMCIA slots for expansion cards also called CardBus cards or PC cards.  Make sure the board you choose has the number and types of slots you require.

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RAM Slots
The type and number of memory slots (along with chipset limitations) determine the type and amount of memory you can install in a PC. Recent motherboards use 168-pin SDRAM DIMMs, 168- or 184-pin Rambus RIMMs, 184-pin DDR-SDRAM DIMMs, 240-pin DIMM, used for DDR2 SDRAM, DDR3 SDRAM and 288-pin DIMM, used for DDR4 SDRAM.
Here is a picture of the four DDR3 memory slots with dual channel support:

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Integrated Functions
Modern motherboards often include embedded functions, such as video and sound (and, less commonly, LAN and SCSI interfaces), that were formerly provided by add-on expansion cards. Embedded components reduce costs, and are better integrated and more reliable. Against those advantages, it may be difficult or impossible to upgrade embedded components, and you pay for those embedded components whether you use them or not. Integrated motherboards are often ideally suited for casual use.






Processor

The processor or CPU is the engine that drives the PC. The CPU is the brain of the computer. It's job is to take information from the various input devices, the operating system, and software and execute the instructions that it has been given. The CPU you use determines how fast the system runs and what operating systems and other software can run on it. Most PCs use processors from Intel (Pentium 4F/ Core 2/Core i3/i5/i7 or Celeron) or or Intel-compatible processors from AMD (Athlon or Duron). CPUs are measured in speed or, to be more accurate, frequency, in megahertz or gigahertz. One hertz is one cycle per second. One megahertz is one million cycles per second, and a gigahertz is one billion cycles per second. The frequency rating indicates the core clock speed of the processor, and it affects only calculations that are going on inside the processor. Processors vary in speed (currently 700 MHz to 3+ GHz), physical connector (Socket 423, Socket 478, Socket 370, Socket A, Slot 1, Slot 2, Slot A, Socket 7, and so on), efficiency at performing various functions, and other respects. As processors have become more sophisticated, they’ve grown in the sheer number of transistors they incorporate. More transistors means more current is passing through them, and more heat is generated. Today’s processors require active coolers (heat sinks with fans attached). Earlier processors used passive coolers (heat sinks without fans), and even earlier ones didn’t require cooling at all. If you run a current processor without a cooler, it’ll fry itself permanently in a matter of seconds. With the number of transistors in processors skyrocketing, cooling is becoming more and more important to processor health.

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Memory
A PC uses Random Access Memory (RAM), also called simply memory, to store the programs and data with which it is currently working. Memory performance is crucial to a speedy system. Slow memory can bottleneck the system and reduce the processor’s effectiveness. RAM is available in many different types, speeds, and physical packages. The amount and type of RAM a system can use depends on its chipset, the type and number of RAM slots available, and other factors. The optimum amount of RAM depends on the operating system you run, how many and which programs you run simultaneously, and other considerations. Adding RAM is often a cost-effective upgrade for older systems, many of which have woefully inadequate RAM to run modern operating systems and programs. RAM is volatile, meaning that it doesn’t store data when powered down. RDRAM (Rambus Dynamic Random Access Memory), and high-bandwidth memory called DDR SDRAM (Double Data Rate Synchronous DRAM). Rambus DRAM runs at higher frequencies than DDR memory. RDRAM is available at 800MHz, 1066MHz, and 1200MHz. Only certain Intel chipsets work with RDRAM, and it’s more expensive than DDR memory. The various speeds are referred to as PC800, PC1066, and PC1200. Like DDR memory, RDRAM transfers data twice during each clock cycle. DDR memory is available at effective speeds up to 400MHz. It’s called both PC3200 and DDR400, depending on where you read it. 400MHz DDR memory actually runs at 200MHz, but it performs data transfers twice per clock cycle.  Specification to look for when choosing RAM is the CAS (Column Access Strobe) latency. The higher the latency, the longer memory takes to respond to data requests. CAS latency time of 2.5 cycles means that after the memory controller has tapped the memory for data from a certain address, it takes two and a half clock cycles for the memory to respond. The lower the CAS latency, the faster the memory. Depending on your motherboard, you may be able to use the BIOS setup program to “force” the computer to run with a lower CAS latency time, but the PC might become unstable.

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Floppy disk drive
The humble floppy disk drive (FDD) was formerly used for everything from booting the PC to storing data to running programs to making backups, but has now been largely relegated to such infrequent uses as making emergency boot diskettes, loading updated device drivers, running diagnostics programs, or "sneakernetting" documents to other systems. Many people don't use their FDDs from one month to the next. The FDD has been officially declared a "legacy" device, and many PCs manufactured after mid-2000 do not have one.

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Optical Drive
CD-ROM drives began to appear on mainstream PCs in the early 1990s, became ubiquitous, and have remained generally unchanged except for improvements in speed and reliability.
Optical technology standards for computers can be divided into three major types:

• CD (compact disc)
• DVD (digital versatile disc)
• BD (Blu-ray disc)

The first type of optical storage that became a widespread computing standard is the CD-ROM. CDROM (compact disc read-only memory) is an optical read-only storage medium based on the original CD-DA (digital audio) format first developed for audio CDs. Other formats, such as CD-R (CD-recordable) and CD-RW (CD-rewritable), expanded the compact disc’s capabilities by making it writable. CD-ROM drives can also play CD-DA (audio) discs and multimedia discs, which makes them popular for listening to music and playing games. CD-R and CD-RW drives, which can write discs as well as read them. which are the follow-on to CD-ROM, and may be used to watch movies or access very large databases—and DVD writers, which function much like CD writers but store about seven times as much data. DVD in simplest terms is a high-capacity CD. In fact, every DVD-ROM drive is a CD-ROM drive; that is, it can read CDs as well as DVDs. (Some older standalone DVD players can’t read CD-R or CD-RW discs, however). Fortunately, all recent optical drives support DVD-ROM, DVD-R/RW and DVD+R/RW media, including dual-layer (DL) DVD+R media, and most also support DVD-RAM. The access time for an optical drive is measured the same way as for PC hard disk drives. In other words, the access time is the delay between the drive receiving the command to read and its actual first reading of a bit of data. Access rates quoted by many manufacturers are an average taken by calculating a series of random reads from a disc. Most optical drives include internal buffers or caches of memory installed on board. These buffers are actual memory chips installed on the drive’s circuit board that enable it to stage or store data in larger segments before sending it to the PC. A typical buffer can range from 2MB up to 8MB or more (depending on the drive). Generally, faster rewritable drives come with more buffer memory to handle the higher transfer rates.

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Hard Disk Drive

The hard disk drive (HDD) is the primary storage device on any PC. Unlike RAM, which retains data only while power remains applied, data written to an HDD remains stored there until you delete it. HDDs are sealed units used for nonvolatile data storage. Nonvolatile, or semipermanent, storage means that the storage device retains the data even when no power is supplied. The basic physical construction of an HDD consists of spinning disks with heads that move over the disks and store data in tracks and sectors. The heads read and write data in concentric rings called tracks. These are divided into segments called sectors, which typically store 512 or 4,096 bytes each. HDDs usually have multiple disks, called platters, that are stacked on top of each other and spin in unison, each with two sides on which the drive stores data. HDD space was formerly a scarce resource that users went to great lengths to conserve. Much like the increases in drive capacity and performance, the speed of the interface has come a long way. Modern interfaces offer data transfer rates of up to 133MBps for Parallel AT Attachment (ATA), up to 600MBps for Serial ATA (SATA) and Serial Attached SCSI (SAS), and up to nearly 2,000MBps for SATA Express. SSDs have changed that game and have been pushing the industry to develop faster interfaces. Over the years, disk drives have been introduced in several industry-standard form factors, usually identified by the approximate size of the platters contained inside the drive. Form factor standards ensure that available drives will fit in the bay, the screw holes will line up, and the standard cables and connections will plug in. Currently, 3 1/2-inch drives are the most popular for desktops, whereas 2 1/2-inch and smaller drives are popular in laptops and other portable devices. Although speeds can vary, modern drives typically spin the platters at either 4,200 rpm, 5,400 rpm, 7,200 rpm, 10,000 rpm, or 15,000 rpm. Most standard-issue drives found in PCs today spin at 7,200 rpm, with high-performance models spinning at 10,000 rpm, although many less-expensive drives still spin at 5,400 rpm.

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Video Adapter

A video adapter, also called a graphics adapter, accepts video data from the computer and converts it into a form the monitor can display. In addition to image quality, the video adapter you use determines the sharpness, number of colors, and stability of the image your monitor displays. Most recent video adapters display text and simple graphics adequately, but video adapters vary greatly in their suitability for use with graphics-intensive software, including games. The video processor (also known as the video chipset, video graphics processor, or GPU) is the heart of any video adapter and essentially defines the card’s functions and performance levels. Two video adapters built using the same chipset will have the same basic capabilities. However, cards built using the same chipset can vary in the clock speeds at which they run the chipset, memory, output ports, and other components, as well as in the amount and type of memory installed. Therefore, performance can vary. Most discrete video adapters rely on their own onboard memory that they use to store video images while processing them. The amount of video memory determines the maximum screen resolution and color depth the device can support, among other features. Although having more video memory is not guaranteed to speed up your video adapter, it can increase the speed if it enables a wider bus (for example, from 256 bits wide to 384 bits wide). Video RAM speed is typically measured in MHz, GHz, or by bandwidth in Mb/Gb or MB/GB per second. Faster memory and faster GPUs produce better gaming performance, but at a higher cost.

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Monitor
The monitor you use ultimately determines the quality of the video you see. Most PCs use flat-panel LCD displays and are an increasingly popular choice. Displays are available in a wide variety of sizes, capabilities, features, and prices, and choosing the right one is not a trivial task. PC monitors come in various sizes, generally ranging from 15 inches to 30 inches in diagonal measurement. Resolution indicates the amount of detail a monitor can render. This quantity is expressed in the number of horizontal and vertical picture elements, or pixels, contained in the screen. The total is usually expressed in the millions of pixels, or megapixels. As the resolution increases, the image consists of a greater number of pixels. With more pixels, you can see more of a given image, or you can view the image in greater detail.

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Sound Adapter and Speakers

All PCs can produce basic warning sounds and audible prompts using their built-in speakers, but for listening to audio CDs, playing games, watching DVDs with full surround sound, using the Internet to make free long-distance telephone calls, using voice-recognition software, and performing other PC audio functions, you'll need a sound card (or embedded motherboard sound adapter) and speakers or headphones.

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Keyboard and Mouse
PCs use several types of devices to accept user input—keyboards for entering text; mice, trackballs, and other pointing devices for working in the Windows graphical environment; and game controllers for playing modern graphical computer games and simulations. One of the most basic system components is the keyboard, which is the primary input device. You use a keyboard to enter commands and data into the system. In computing, a mouse is a pointing device that detects two-dimensional motion relative to a surface. This motion is typically translated into the motion of a pointer on a display, which allows for fine control of a graphical user interface.

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PC Case
The case (or chassis) is the outer shell that contains the PC and all internal peripheral devices. PC cases are available in a bewildering array of sizes, shapes, and prices. Form factor is the most important thing about a case because it determines which motherboards and which power supplies fit that case. Cases are available in a variety of sizes and orientations, including low-profile desktop, standard desktop, micro-tower (for microATX boards), mini-tower, mid-tower, and full-tower. Low-profile cases are popular for mass-market and business-oriented PCs, but we see little purpose for them.

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Power Supply Unit
The power supply unite (PSU) provides regulated power to all system components and cooling airflow to keep components from overheating. The power supply is not only one of the most important parts in a PC. I consider the power supply the foundation of the system and am willing to spend a little extra to get a more robust and reliable unit. The power supply is critical because it supplies electrical power to every other component in the system. A malfunctioning power supply not only can cause other components in the system to malfunction, but can damage the other components in your computer by delivering improper or erratic voltages. The power supply in a conventional desktop system is designed to convert either 120V (nominal) 60Hz AC (alternating current) or 240V (nominal) 50Hz AC power into +3.3V, +5V, and +12V DC (direct current) power.

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