Overview. Motherboards 1

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1 Motherboards 1 Motherboards Overview... 1 Form Factors... 2 ATX... 2 MicroATX... 4 BTX... 4 ITX... 4 Mini-ITX... 4 nanoitx... 5 picoitx... 5 Sockets... 5 Pin Grid Array (PGA)... 5 PGA Variants... 6 Zero-Insertion Force (ZIF) Sockets... 6 Land Grid Array (LGA)... 6 Loading Plate... 6 Intel Sockets... 6 AMD Sockets... 7 Chipsets... 8 Chipset Architecture and Components... 8 Intel Chipsets The Relationship Between Sockets and Chipsets Chipset Naming Convention Busses BIOS Power On System Test (POST) CMOS Setup The Boot Process and the Bootstrap Loader BIOS-Loaded Drivers Flashing the BIOS CMOS RAM and the Real Time Clock Password Protection Losing CMOS Settings Replacing the CMOS Battery Overview This document describes motherboard form factors, sockets, chipsets, expansion bus and slots, BIOS, and other components. The table to the right from canardpc.com/statscpuzcm-en.html outlines motherboard market shares as of 2/10/2010. It Market Share Company (%) Asus 29.2 Gigabyte 17 Micostar International (MSI) 8.9 Dell 4.6 Intel 3.4

2 Motherboards 2 should be noted that Dell and HP do not manufacture their own boards. Lenova 3.1 Acer 3.1 Elitegroup Computer Systems (ECS) 2.9 Biostar 2.3 HP 2.2 Others 23.4 Form Factors Form factors define motherboard dimensions, mounting hole positions, and power supply connections. The table below provides a historical overview of form factors. Release Date Name Dimensions Comments 1981 PC 9" x 13" 1983 XT 9" x 13" 1984 AT 12" x13.8" 1986 XT-286 9" x 13" 1984 Baby AT 9" x 13" Legacy 1987 LPX 1996 NLX 1998 WTX 14" x16.75 ATX* 12 x 9.6 Sponsored by Intel - Still the most microatx* 9.9 x 9.6 important form factor family flexatx 9 x 7.5 today. BTX 12.8 x 10.5 Sponsored by Intel - No longer 2003 microbtx 10.4 x 10.5 supported as of 2006 picobtx 8.0 x Mini-ITX* 6.7" x 6.7' Sponsored by VIA. Mini-ITX is Nano-ITX 4.7 x 4.7 also sponsored by Intel 2007 Pico-ITX 3.9 x 2.8 * The most relevant form factors today ATX Date Version ATX (Advanced Technology Extended) is a computer form 1996 ATX factor created by Intel in 1995 as an open specification. It 1997 ATX v 2.01 encompasses computer case, motherboard, and power supply 2000 ATX v 2.03 design. The ATX specification has been revised several times 2002 ATX v 2.1 since its original release, as indicated in the table to the left ATX v 2.2 The ATX board itself measures a maximum of 12 by 9.6 inches. It provides sufficient space for about seven expansion slots, which are spaced at the conventional 0.8 inches apart. Mounting holes for the ATX family of form factors is shown in the diagram below:

3 Motherboards 3 Form Factor Mounting holes Maximum Size ATX A, C, F, G, H, J, K, L, M 12" x 9.6" microatx B, C, F, H, J, L, M, R, S 9.6" x 9.6" FlexATX B, C, F, H, J, S 9.0" x 7.5" miniitx 1 C, F, H, J 6.6 x miniitx (discussed in a later section) is the FlexATX form factor scaled to a minimum size allowing for the C, F, H and J ATX mounting holes. Following is a list of guidelines, taken from specification documents, that apply to both ATX and microatx form factors. Feature Comment Power Connector Should be right edge of board near the processor Back panel I/O Aperture Must be 6.25" x 1.75" Disk I/O Connectors Should be front edge of board near the drive bays. Front Panel I/O Connectors Should be front edge of board.

4 Motherboards 4 Feature Memory Module Connectors Expansion Slot Connectors Comment Should be between processor and expansion slots, or between processor and disk I/O connectors. Must be below the CPU parallel to the short edge. MicroATX The MicroATX board itself measures a maximum of 9.6 by 9.6 inches which allows for about four expansion slots. These slots can be any combination of PCI, PCI-X, PCI-e, CNR, and AGP. Most ATX specifications also apply to microatx. BTX Intel announced the (Balanced Technology Extended) BTX standard in 2003 with the goal of optimizing computer cooling efficiency. It is not backwards compatible with the ATX form factor, but it does use the same power connector. All BTX boards are 10.5 inches deep and can vary in width per designation as indicated in the table below. Designation Max Width # Card Slots BTX 12.8" 7 microbtx 10.4" 4 nanobtx picobyx 8" 1 In 2007, Intel announced that it will no longer build motherboards based on the BTX form factor, but will support legacy boards.. The last Intel motherboard manufactured to BTX specifications contained the 965 chipset (released in 2006) which supported the Intel Pentium 4, Pentium 4 HT, Pentium D, Celeron D, Core2 Extreme, and Core2 Duo processors. The most recent BTX motherboard that the instructor could find on pricewatch.com was manufactured by Elitegroup Computer Systems (ECS) and had an LGA775 socket and Intel X38 chipset (released in 2007) that supported Core 2 Quad/Core 2 Duo/Core 2 Extreme processors ITX The ITX form factor family consists of three members: miniitx, nanoitx, and picoitx. They are open source specification created by VIA and adopted by the Small Form Factor Special Interest Group (SFF-SIG). Mini-ITX The Mini-ITX board itself measures a maximum of 6.7 by 6.7 inches which is sufficient for about one expansion slot. It is the FlexATA form factor scaled around ATX mounting holes C, F, H, and J. That means that a miniitx motherboard could theoretically be used in a flexata, microata, or ATA case. However, most miniitx are deployed in very

5 Motherboards 5 small cases specially created specifically for them. The table below provides an outline of current miniitx motherboard manufacturers. Manufacturer Intel Jetway VIA Zotac MSI Processors Supported Embedded Atom D410, 510( passively cooled) Atom N 230 (fanless), 330 (dual core) LGA775 processors (Core 2 dual and quad core) VIA C7 Intel Atom N230, N330 VIA C7 Atom n230 (fanless); N330 (dual core) LGA 775 processors Atom 230 (fanless) nanoitx The nanoitx form factor measures 4.7" x 4.7". It appears that no manufacturer is currently building a nanoitx motherboards. picoitx The picoitx form factor (3.9" x 2.8") is only produced by VIA in one model. It is primary use is in vehicles. Sockets Sockets are the receptacles that connect CPUs to motherboards. There are two basic types of CPU sockets in use today: Ping Grid Array (PGA) and Land Grid Array(LGA): Pin Grid Array (PGA) A PGA CPU (depicted right) is built with an array of pins protruding from its lower surface, which can be mated with a motherboard socket that is constructed with a matching array of holes. Pins are spaced approximately 0.1" apart so roughly 100 pins can be placed per square inch of CPU surface area. Shown left is a variant of PGA known as Staggered Pin Grid Array (SPGA). SPGA provides for more pin density than PGA by offsetting rows. Compare SPGA to PGA, shown to the right. PGA SPGA

6 Motherboards 6 PGA Variants A standard PGA or SPGA CPU has the die facing upward on the bottom of the package substrate. A new approach has been developed, known as The Flip-chip pin grid array (FC-PGA or FCPGA), in which CPU die faces downwards on the top of the substrate with the back of the die exposed. This allows the die to have more direct contact with the heat sink or other cooling mechanism. As mentioned above, the pin spacing for a regular PGA sockets is approximately 0.1". A variant has been developed, known as micropga (mpga), in which spacing is cut in half to approximately 0.05". This socket type is often used with mobile processors to save space. Different materials have been used as CPU package substrates which are known as minor PGA variants, as listed in the table below. PGA Variants Plastic PGA (PPGA) Ceramic PGA (CPGA) Organic PGA (OPGA) CPU Package Substrate Plastic Ceramic Organic Plastic Zero-Insertion Force (ZIF) Sockets ZIF sockets are used on most PGA motherboards to make CPUs easier to install, and to help prevent bending pins. Before a CPU is inserted into a ZIF socket, a lever on the side of the socket is moved, pushing away the spring-loaded contacts. The CPU is then essentially just dropped into the socket. The lever is then moved back, allowing the contacts to close and securely grip the CPU pins. Land Grid Array (LGA) An LGA CPU (shown left) is built with an array of lands, or pads, along its lower surface, which can be mated with a motherboard socket that is constructed with a matching array of short, stocky pins. Because of the higher pin density that can be achieved with LGA, it is the predominant socket technology used today. Loading Plate Instead of a ZIF retaining device, LGA CPUs are held in place by a hinged loading plate that swings down to cover the CPU. Intel Sockets A table of modern Intel sockets is provided below: Package/Pins Name Intro /Layout Supported CPUs Slot pin slot Pentium II/III SECC, Celeron SEPP, Cyrix II, C3

7 Motherboards 7 Name Intro Socket Socket Socket 478 Socket N 2000 Socket Socket LGA 775 Socket T LGA 771 Socket J LGA 1156 Socket H Package/Pins /Layout SPGA/370 /37 x 37 SPGA/423 /39 x 39 mpga/478 /26 x 26 mpga/ x 25 mpga/ x 25 LGA/ x 33 LGA/ x 33 LGA/ x 40 Supported CPUs Pentium III, Celeron, VIA Cyrix III, C3 Pentium 4 (Willamette only) Intel Pentium 4, Celeron, Pentium 4, Pentium 4 M Xeon (server) Xeon (server) Intel Pentium 4, Pentium D, Celeron, Celeron D, Pentium XE, Core 2 Duo, Core 2 Quad, Xeon Xeon (server) Core i7 (800 series), Core i5 (700, 600 series), Core i3 (500 series), Xeon (X3400, L3400 series), Pentium (G6000 series), Celeron (G1000 series) Intel Core i7 (900 series), Xeon (server) LGA 1366 LGA/ Socket B 41 x 43 LGA LGA/1567 Xeon (6500/7500 series) LGA LGA/1155 AMD Sockets A table of modern AMD sockets is provided below: Supports Sandy Bridge processors (replacement for LGA 1156) Name Intro Package/Pins /Layout Supported CPUs Slot A pin slot Athlon Socket SPGA/462 Athlon, Duron, Athlon XP, Athlon XP-M, /37 x 37 Athlon MP, Sempron Socket PGA/940 Athlon 64 FX, Opteron (servers) /31 x 31 Socket mpga/939 Athlon 64, Athlon 64 FX, Athlon 64 X2, Opteron 31 x 31 Socket AM mpga/940 Athlon 64, Athlon 64 X2 31 x 31 Socket F 2006 LGA/1207 Athlon 64 FX, Opteron (Replaces Socket 940 for

8 Motherboards 8 Name Intro Package/Pins /Layout Supported CPUs /35x35x2 servers) Socket AM mpga/940 Athlon 64, Athlon 64 X2, Phenom 31 x 31 Socket AM mpga/941 Phenom II, Athlon II, Sempron 31 x 31 Socket C LGA/1207 Opteron (Replaces Socket F for servers) Socket C LGA/1974 Opteron (Replaces Socket F for servers) Notes: 1. Socket 939 supports (only) DDR memory whereas AM2 supports (only) DDR2 memory. 2. Socket AM2+ improves HyperTransport speed over socket AM2 (from 1 GHz to 2.6 GHz) and adds split power planes: one for the CPU cores, and the other for the Integrated Memory controller (IMC). 3. AM2 processors will work on AM2+ motherboards, and vice versa - but only AM2 performance is realized. 4. The built-in memory controller in AM2/AM2+ processors only supports DDR2 memory. 5. The principal change from AM2+ to AM3 is that AM3 processors support both DDR2 and DDR3 memory. Chipsets Chipsets define motherboard features and capabilities. When you purchase a motherboard, the chipset should be one of the primary considerations. Chipset Architecture and Components Historically, a chipset has been composed of two main chips called a Northbridge and Southbridge, as shown in the diagram below:

9 Motherboards 9 The Northbridge connects high-speed components, such as the memory controller and video controller, directly to the CPU via the front-side bus. The Southbridge connects slower speed components to the CPU indirectly through the expansion bus. A modern view of chipsets is shown below. With it, the memory and video controllers are incorporated into the CPU, and the front-side bus and Northbridge are eliminated. This configuration increases the speed of memory and graphics

10 Motherboards 10 In 2003, AMD was the first CPU manufacturer to implement the above model with its deployement of the Direct Connect Architecture into its 64 bit chipsets. Intel did the same in 2009 with the implementation of its QuickPath Interconnect technology into its Nehalem line of CPUs. With LGA 1366 Nehalem CPUs, the memory controller is incorporated directly into the die of each CPU. With the LGA 1156 and LGA 1155 Nehalem CPUs, the entire Northbridge is incorporated into the CPU die. Intel Chipsets Intel started making chipsets in 1989 and has been the industry leader in this field ever since. The table below provides a list of Intel chipsets in chronological order. It is divided into three categories according to Southbridge connectivity. Category 1 - Those connected by the PCI bus - with a throughput of 133 MBps. This includes the original 400 series chipsets. Category 2 - Those connected with the Advanced Hub Architecture (AHA) - with a throughput of 266 MBps. This includes the 800 series chipsets. From this point forward, Intel refers to the Northbridge as the IO Hub (IOH) and the Southbridge as the IO Controller Hub (ICH). Category 3 - Those connected with the Direct Media Interface version 1.0 (DMI 1.0) - with a throughput of 1 GBps in each direction. This includes the 900 and 5x series chips. DMI v 1.0 is essentially a PCI-e x4 v 1.1 connection. Category 4 - Those connected with DMI 2.0, including the latest 6x series, with a throughput of Chipset Series Chip Interconnection Supported Processors and Other Features 420xx P4 (486) 430xx P5 (Pentium), EDO memory PCI bus 440xx P6 (Pentium Pro, II, III), AGP, SDRAM 450xx P6 workstation (Pentium Pro, II, III, Xeon), SDRAM 8xx AHA PII, PIII, P4, AGP, DDR memory 9xx Pentium 4/D, Core 2, PCI Express, DDR2 memory 3x Core 2, PCI Express, DDR2/DDR3 memory DMI 4x Core 2, PCI Express 2.x, DDR2/DDR3 memory 5x Nehalem (Core i series), PCI Express 2.x 6x DMI 2.0 Sandy Bridge (Core i series Second Generation) Starting with Nehalem, the Southbridge is connected directly to the CPU. The table below outlines the top providers of chipsets for Intel processors as of 2/9/2010 (according to

11 Motherboards 11 Manufacturer Market Share (%) Intel 82.5 VIA 5.8 nvidia 4.9 SiS 4.3 ATi 2.2 The Relationship Between Sockets and Chipsets The latest Intel sockets and chipsets found on motherboards are listed in the table below. Chipsets Socket Desktop Server LGA 1156 H55, H57, P55, Q , 3420, 3450 LGA 1366 X , 5520 LGA 1155 P67, H67, H65, H61, Q67 Chipset Naming Convention Ever since the introduction of the 3x series of desktop chipsets, chipset names have been comprised of two digits with a one-or-two letter prefix. Generally, the newer and more capable the chipset, the larger the given number. The chipset prefixes mean the following: Prefix H P X Q Consumer Segment / Comments Mainstream. Supports on die graphics Mainstream performance. Supports discrete graphics, overclocking. Leading-edge performance. Supports discrete graphics, overclocking Business. Supports on die graphics and management features. Busses The following table outlines various bus options that may be available in a modern computer: Release Bus Date Name Speed Width (bits) Throughput 1991 PC Card (PCMCIA Card) 33 MHz MB/s 1993 PCI v1 33 MHz MB/s 1993 PCI v MHz MB/s 1995 CardBus 33 MHz MB/s 1997 AGP MHz MB/s

12 Motherboards PCI-X v1 1 66/133 MHz /1056 MB/s 2000 AGP MB/s 2000 USB v2 480 Mb/s 1 60 MB/s 2002 AGP MHz MB/s 2003 PCI-X v2 1,2 266/533 MHz /4.2 GB/s 2003 ExpressCard v1 PCIe v1 = 2.5 GT/s USB v2 = 480 Mb/s 1 serial lane PCIe v1: 250 MB/s USB v2: 60 MB/s PCI Express 2.5 GT/s 3 per lane x (1 lane) = 250 MB/s 5 per lane (PCIe) v1 one direction 16x (16 lanes) = 4 GB/s 5.0 GT/s per lane 1x (1 lane) = 500 MB/s 2007 PCIe v2 1 per lane one directional 16x (16 lanes) = 8 GB/s 2008 USB v3 5 Gb/s MB/s PCI v2 = 5.0 GT/s 500 MB/s 2009 ExpressCard v2 1 serial lane USB v3 = 5 Gb/s 625 MB/s Q4 PCIe v GT/s per lane 1x (1 lane) = 1 GB/s 1 per lane 2010 one direciton 16x (16 lane) = 16 GB/s 1. Due to the cost of its 64-bit technology, PCI-X is implemented primarily in server systems. 2. PCI-X v2 is not widely deployed because it was overshadowed by PCIe v1. 3. Giga transfer per second (GT/s) is a measure of raw (unencoded) serial transfer (one bit at a time). PCIe uses 8b/10b encoding which consumes 20% of the bandwidth. Therefore, one calculates the throughput of a 2.5 GT/s lane as follows: 2.5 GT/s x 1 bit/transfer x 80% = 2.0 Gb/s 2.0 Gb/s / 8 bits/byte =.25 GB/s = 250 MB/s 4. Actually, a PCIe lane has a bus width of 2-bits when used in full duplex mode. Each lane consists of two pairs of differentially signaled serial wires and is full-duplex capable. 5. In full-duplex mode, the throughput for PCIe is theoretically doubled those listed in this table. 6. It will probably be late 2011 or 2012 before products using PCIe v3 enter the market place. The chart below compares the throughput (MB/s) of various bus types commonly used in modern computers.

13 Motherboards 13 USB 3 PCIe 2 (x1) PCIe 1 (x1) PCI-X 1 (133) PCI-X 1 (66) PCI 2 PCI 1 USB 2 PCI-X 2 (266) PCIe 1 (x16) PCI-X (533) PCIe 2 (x16) MB/s BIOS The Basic Input/Output Service (BIOS) is a set of programs stored in a read-only memory (ROM) chip connected to the Southbridge that perform the following four functions: Function Power-On System Test CMOS Setup Bootstrap loader Driver Loader Description Hardware tests performed at startup A utility for viewing and modifying CMOS setting Code that finds the boot sector of a loadable operating system Loads basic drivers need before an operating system is running. Power On System Test (POST) The POST utility tests a computer's main memory, busses, and devices, and invokes the BIOSs of devices that have their own specific BIOS, such as video adapters, network adapters, and RAID controllers. Any POST errors are displayed as text messages on the screen. Errors are often accompanied by beep codes which are helpful for video errors that cannot be displayed. The interpretation of beep codes varies between BIOS manufacturers and motherboards. BIOS or motherboard documentation should be consulted for their meaning.

14 Motherboards 14 CMOS Setup The BIOS CMOS Setup utility is used to update setting in CMOS as well as set the realtime clock (RTC). The CMOS Setup utility is invoked by pressing a key identified in a message displayed at the beginning of system POST. Example message: Press <F2> to enter Setup The key required to enter CMOS Setup is specific to each type of BIOS, as given in the table below: Key F1 or Del F1 or F2 Del Esc F10 1 BIOS American Megatrends Inc (AMI) BIOS Phoenix BIOS Award BIOS Microid Research (MR) BIOS Compaq The Boot Process and the Bootstrap Loader Understanding the boot process is important when troubleshooting problems that occur during startup. The basic boot process is as follows: The CPU starts the boot process when it receives voltage after the power button is depressed. The first thing that it does is read the level of the power good wire to determine if the voltage provided by the power supply is adequate. If the power supply is adequate then the CPU passes control to the BIOS which starts the POST. During POST, the BIOS check critical system hardware. At the end of POST, the BIOS passes control to the bootstrap loader which attempts to locate the boot sector of the first boot device listed in CMOS. If this fails, it goes down the list of boot devices in order until one is found that has a valid boot sector. After a valid boot sector is found (one that can identify the location of an operating system), control is passed to the operating system. The operating system completes the boot process. BIOS-Loaded Drivers The BIOS loads drivers for hardware that needs to be up and running before the operating system is booted, including the following: Hard Drives Optical Drive Floppy Drive USB Controller Video Adapter Network Adapter RAID Controller Keyboard Drivers for hardware such as video adapters, network adapters, and RAID controllers are often loaded by a BIOS within the device itself. 1 Your HP lab computer uses the F10 key to invoke CMOS Setup.

15 Motherboards 15 Flashing the BIOS The ROM chip is made up of solid state flash memory that allows the BIOS to be updated or restored programmatically. Updating the BIOS in this manner is known as flashing the BIOS. Since a power fluctuation can corrupt the BIOS when flashing, it best to do so only when absolutely necessary, and only after making a complete BIOS backup. The manufacturer of your laboratory computers, HP, provides the following methods for flashing the BIOS. Note that only the ROMPaq diskette method creates a BIOS backup. Name DOS Flash HPQFlash ROMPaq CD ROMPaq Diskette Description DOS based utility that can be used locally or with a Preboot execution Environment (PXE) network adapter to update or restore the system BIOS. Windows based utility to locally update or restore the system BIOS Creates a bootable CD that can be used to locally restore or upgrade the system BIOS Creates a bootable 1.44 diskette that can be used to locally restore or upgrade the system BIOS Backup Made No No No Yes CMOS RAM and the Real Time Clock The CMOS RAM and Real-Time clock (RTC) are normally combined into one chip that is incorporated into the Southbridge. The function of CMOS RAM (known simply as CMOS) is to store system parameters required by the BIOS at boot up. The function of the RTC is to maintain the system date and time. A small amount of electricity is required to run the RTC and to maintain data in CMOS. This electricity is supplied externally as long as the computer is plugged in. When the computer is unplugged, a small battery located on the motherboard provides the electricity. Most CMOS setup programs have similar basic options, include the following: System information Device options Boot order Date and Time settings Power Management Password protection Password Protection Many CMOS setup programs allow you to setup a boot password and a password to enter setup itself. These passwords are stored in CMOS and can be reset if you forget them - in

16 Motherboards 16 various ways. The motherboards in your HP laboratory computer, for example, have a jumper that allows you to clear password settings. Losing CMOS Settings As mentioned above, CMOS is dependent upon a small battery mounted on the motherboard to maintain its settings. If the battery gets to the point where it is not holding adequate charge, then the first symptom that may occurs is a slippage in system time. If the battery goes dead, the system time will reset itself to January 1st and CMOS setting may be lost or set to default values. On systems built after 2002, however, the CMOS should fall back to factory default settings. Factory defaults may allow the system to boot, but there is a likelihood that CMOS configuration errors may occur. Some CMOS setup utilities (such as the one used in your laboratory computers) will allow the user to backup copies of CMOS configuration settings. Replacing the CMOS Battery Refer to the motherboard documentation for proper procedures to replace the CMOS battery. If documentation is not available, then use the following steps: Backup CMOS settings. Data may need to be restored after the new battery is installed. If possible, obtain a replacement battery in advance with the proper voltage. Turn off the computer. You have the option of unplugging the computer or leaving it plugged in. Unplugging it is the safest choice for both you and the equipment, but leaving it plugged in allows a small amount of voltage to be supplied to the CMOS during battery replacement so that settings will not be lost. Remove the system unit cover and use proper anti-static procedures from this point forward. Locate the CMOS battery on the motherboard. It will be cylindrical in shape and resemble a watch battery. Batteries have a + and - orientation. Make sure you make note of this orientation when you take the old battery out so that you can use it when putting the new back in. Following are the procedure for removing the battery from your laboratory computer.

17 Motherboards Release the battery from its holder by squeezing the metal clamp that extends above one edge of the battery. When the battery pops up, lift it out (see diagram to the right). 2.Insert the new battery by sliding one edge under the holder lip with positive side up. Push the other edge down until the clamp snaps over the other edge of the battery. Restart the computer, go to CMOS setup, and restore or manually re-enter any lost settings.