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UNIT #3 – “THE SYSTEM BOARD AND TROUBLE SHOOTING
FUNDAMENTALS”
The system Board
I. TYPES OF SYSTEM BOARDS
A. AT
1. Oldest type
2. Uses p8 p9 connectors
3. 30.5 cm x 33 cm
B. BABY AT
1. Uses p8 p9 connectors
2. 33 cm x 22c
C. ATX
1. Better Layout
2. Includes power-0n switch
3. Extra power connections for more fans
4. P1 connector
5. 30.5 cm x 24.4 cm
D. Mini ATX
1. More compact design
2. 28.4 cm x 20.8 cm
II. Main components of a system board
A. CPU chipset
B. System Clock
C. ROM BIOS
D. CMOS (chip & battery)
E. RAM
F. System Bus
G. Jumpers and dip switches
H. Ports directly attached to board
I. Power supply connections
J. EIDE controllers
K. Floppy Drive controllers
L. PCI slots
III. Things to look for when purchasing a system board
A. CPU speed and type of CPU socket
B. Chipset
C. Memory Cache Size Type 1
D. Expansion slots (ISA-PCI-AGP)
E.
F.
G.
H.
I.
J.
K.
L.
Type of memory
Max RAM
Type of case
ROM BIOS
Type of keyboard connector
Presence of other ports or bus slots
Presence or absence of IDE and SCSI controller
Presence or absence of COM ports, LPT port, and mouse ports
IV. Ask the following Questions when selecting as system board
A. Will long expansion slots interfere with the CPU or other important devices?
B. How many different CPU’s can the board support?
C. What bus speeds, type of memory, and system BIOS does the board support?
D. Does the board use many embedded devices?
E. Does the board fit the case?
F. Does the board support my expansion cards?
G. What is the warranty?
H. How extensive and user-friendly is the documentation?
I. How much support does the manufacturer supply for the board?
V. The system clock
A. megahertz MHz used to measure clock frequency
B. one MHz = 1,000,000 beats per second
C. Today’s CPU’s can two activities per clock cycle
D. It is more accurate to refer to CPU frequency not speed
E. Wait states are used to allow the system board components to catch up to the
CPU
F. Slower Dynamic RAM created wait states.
G. Today DDR RAM is popular to speed up the process also CACHE
VI. CPU and the chipset
A. Attributes to rate the CPU
1. CPU speed measured in MHz
2. Efficiency of the programming code (number of instruction sets
needed to accomplish a task. The fewer the better
3. Word size (largest number of bits the CPU can process in one
operation
4. Data path (same as system bus size) is how many bits can be sent to
the processor. Sometimes more can be sent than the processor can
processes in a cycle.
5. Maximum number of memory addresses (max number for Pentium
CPU’s is 4096 megabytes)
6. The amount of memory included with the CPU. (storage for
instruction sets built inside the chip housing – Level 1 cache)
7. Multiprocessing ability
8. Special functionality (like MMX for multimedia)
A. Relating CPU Attributes to Bus Architechure
1. 20 wires in a bus would allow for a maximum of 1111 1111 1111 1111
1111 bits in binary or 1,048,576 unique addresses.
2. The first Pentium could use 32x2 word size / a 64 bit path / w 4096
Mb of memory addresses (4,096,000,000) unique addresses
3. The Pentium III and IV can quad-pipeline (32x4 word size)
B. Voltages used by CPU’s
1. Really old CPU’s 5 volts
2. Old CPU’s 3.3 volts
3. Newer CPU’s 2.8 volts
VII.
Pentium and Competitors
A. Comparing Chips
1. System boards have many bus speeds (only the fastest goes to the
CPU)
3. The memory bus is the fastest and connects the CPU to RAM(also
called the system bus)
4. Common speeds for the memory bus are 100-133-200-266
5. Processor speed is the speed at which the processor operates internally.
6. If the CPU is faster than the memory bus, the difference in speed is
called the multiplier. (multipliers can be set by jumpers on the
motherboard)
7. Common multipliers are 1.5 2 2.5 3 3.5 4
B. Memory Cache
1. Cache is SRAM (Static RAM) Holds its memory as long as there is
power.
2. DRAM (Dynamic RAM) must be refreshed
3. Level 1 cache is on CPU microchip (called internal cache)
4. Level 2 cache is outside microchip but sometimes inside overall
housing (called external cache)
5. The bus between the CPU and level 2 cache is called the “Backside
bus”
6. The bus between RAM and the CPU is called the “Frontside Bus”
7. On some Pentium III’s the L2 cache is a part of the same core as the
CPU. It is hard to tell the difference between L1 and L2 cache.
(Called ATC Advanced Transfer Cache) It has a 256 bit bus and runs
at the same speed as the CPU
8. On other Pentium III’s the L2 cache is outside the core but is called
discrete cache. It runs on a 64 data bus and runs at half the speed of
the CPU
C. Types of CPU’s
1. CISC – Complex Instruction Set Computer Most Intel processors –
has a large number of instruction sets on the chip
2. RISC – Reduced Instruction Set Computer has fewer instruction sets
on the chip and can run faster for some applications. Video and
Telecommunications.
3. Intel stays with CISC for backward compatability although Pentium II
uses a combination
4. Others use some RISC processors
a. AMD – K6 processor
b. Motorola – Macintosh
c. Sun Microsystems
VIII. CPU Cooling Fans
A. Intel has a 185 degree heat limit
B. Good fans cool to 90-110 degrees
C. Ball bearing cooling fans last longer
D. Some chips has a heat sink and a cooling fan
E. RISC processors do not generally need a fan
IX. Form factors for CPU’s
A. SEP – Single Edge Processor
B. SECC – Single Edge Contact Cartridge
C. SECC – Single Edge Contact Cartridge, Version 2
D. PPGA – Plastic Pin Grid Array
E. FC-PGA – Flip Chip Plastic Pin Grid Array
X. Types of sockets
A. Socket 370 or PGA370 Socket
1. Pentium III FC-PGA
2. Celeron PPGA
3. Cyrix III
B. Slot 1 or SC242
1. Pentium II
2. Pentium III
C. Slot A – AMD Athlon
D. Slot 2 or SC330
1. Pentium II Xeon
2. Pentium III Xeon
E. PGA – Pins are evenly aligned
F. SPGA – Pins are staggered
G. Old sockets were called LIF (low insertion force sockets) It was still easy to
damage the CPU
H. Today’s sockets are called ZIF (zero insertion force)
XI . Voltages
A. Single Voltage CPU’s use one voltage.
B. Dual Voltage CPU’s use one voltage for external functions and another for
internal functions.
XII. Chip Sets
A. Chipsets for Intell
1. i800 series
2. Orion 450 series
3. Natoma 440 series
4. Triton III 430 series
B. Manufacturers
1. Intel
2. Cyrix
3. Silicon Integrated Systems Corp. (SiS)
4. Ali
5. Standard Microsystems Corp.
6. United Microsystems Corp.
7. VIA Technology, Inc. combined with AMD, Inc.
8. VLSI Technology
XIII. ROM BIOS
A. Considerations for ROM BIOS
1. Does the BIOS support Plug and Play
2. Does the BIOS support large hard drives
3. Is the BIOS chip a Flash ROM chip
B. Updating BIOS – When BIOS is incompatible with hardware or software it
can either be updated or software can be provided that will get around the
problem. Usually, manufacturers will provide the software.
C. Flash ROM
1. To upgrade flash ROM you should follow the directions that came
with your system board and your upgrade software.
2. Be sure to set a jumper on the system board telling the BIOS to expect
an upgrade
3. Copy the upgrade BIOS software to a bootable disk
4. Boot from the disk and follow the menu options to upgrade the BIOS
5. Set the jumper back to its original setting, reboot the system, and
verify that all is working.
XIV. Busses and Expansion Slots
A. What busses do
1. Provide electrical power for chips on the system board
2. Cary control signals
3. Pass memory addresses
4. Cary DATA
B. EISA Bus – for legacy cards
C. Universal Serial Bus Host controller allows for hot swapping
D. Fire Wire or i.Link or IEEE1394 can handle speeds of up to 1.2 Gbps uses
host controller and one set of system resources (IRQ, I/O address range, DMA
channel)
E. IEEE 1394.3 standard allows cameras and scanners to send data to a printer
w/o the computer.
F. Firewire and USB are supported by Windows 98, NT, 2000, 2003 Server, and
XP.
G. PCI buss
1. one advantage is that devices can run at one speed while the CPU runs
at a different speed thus eliminating wait states.
2. PCI acts as the go-between between the expansion bus and the
memory bus.
3. The PCI controller takes data from the CPU at top speed, buffers it and
sends it on at a slower speed.
H. The PCI bus can connect
1. Network cards
2. Adaptor cards
3. Video cards
4. Sound cards
5. SCSI controllers
6. RAID controllers
I. Accelerated Graphics Port – Directly connects to the CPU / can support higher
speeds.