The motherboard is the key circuit board holding the essential processing parts of a computer. It allows all the parts of your computer to receive power and communicate with one another. It is usually screwed to the case along its largest face, which could be the bottom or the side of the case depending on the form factor and orientation. The form factor describes the shape and layout of the motherboard. It affects where individual components go and the shape of the computer’s case. Attached directly to the motherboard are the CPU, RAM, expansion cards, networking, video, and audio components.
Figures: Above: An older motherboard, Below: the Intel Z77 motherboard.
ATX (Advanced Technology eXtended) is a motherboard form factor specification developed by Intel in 1995. A full-size ATX board is 12 × 9.6 in (305 × 244 mm). It was the first big change in the computer case, motherboard, and power supply design in many years, improving the standardization and interchangeability of parts. The specification defines the key mechanical dimensions, mounting point, I/O panel, power and connector interfaces between a computer case, a motherboard, and a power supply. The specification has been revised numerous times since 1995, the most recent being version 2.3, released in 2007.
Standards: ATX, standards for smaller boards: microATX, FlexATX, and mini-ITX.
Figure: the Intel Z77 motherboard (Plan View). (Intel, 2014b)
|1. 12V Processor Core Voltage
Connector (8 pins)
|15. POST Code LED Display||29. High Definition (HD) Audio AC97 Front Panel Header|
|2. Voltage Regulator status LEDs||16. Front Panel Header||30. CMOS RAM Battery|
|3. Processor Socket (LGA1155)||17. USB 2.0 Dual-Port Header (black)||31. Rear Chassis Fan Header (4 pins)|
|4. Processor Fan Header (4 pins)||18. Chassis Intrusion Header||32. 5 port audio with S/PDIF|
|5. Memory Slots||19. BIOS Configuration Jumper||33. Intel Gigabit (10/100/1000 Mb/s) Ethernet LAN|
|6. Front Chassis Fan Header (4 pins)||20. Consumer IR (CIR) headers||34. IEEE 1394a port|
|7. Onboard Speaker||21. USB 3.0 Front Panel Connector
|35. External Serial ATA (eSATA) port (3 Gb/s)|
|8. Main Power Connector (2×12 pin)||22. S/PDIF out Header (4 pins)||36. USB ports:
4 USB 3.0 ports (blue)
2 USB 2.0 ports (black)
|9. Onboard Power Button||23. Diagnostic Status LEDs||37. Graphics ports|
|10. +5V Standby Power Indicator LED||24. Auxiliary chassis fan header (4 pins)||38. Back to BIOS button|
|11. SATA 3.0 Connector (black)||25. IEEE 1394a front panel header||39. PS/2 port|
|12. SATA Ports:
(4 SATA 6.0 ports (blue & grey)
(2 SATA 3.0 ports (black)
|26. PCI Express 2.0 x1 connector||40. USB 2.0 ports (yellow)
2 high current/ fast charging
|13. Intel z77 Express Chipset||27. Conventional PCI bus connector||41. Voltage Regulator modules
with heat sinks
|14. Alternate Front Panel Power LED
|28. PCI Express 3.0 x16 connector|
|HEAT SINKS, FANS||PC POWER SUPPLY||Graphics, Sound and Network Card|
This post contains the content of book Computer Hardware_ Hardware Components and Internal PC Connection