About SMPS and their Colour voltage uses
SMPS ( Switch Mode Power Supply)
SMPS is Switching Power Supply , Which Provide Regulated DC Voltage to Motherboard , Hard Disk, DVD Writer etc.
There are two type of SMPS
1-AT (Advanced Technology): This Power Supply has 12 pin and 6,6 pin Two Connector. It is used old Motherboard like P1, P2 and P3.
2-ATX (Advanced Technology Extended): This Power Supply has 20 or 20+4 pin .It is used new Motherboard like P4, Dual Core (DC), Core 2 Duo (C2D), Core 2 Quad (C2Q) and Core i3, i5, i7.
Different between AT and ATX:
AT (Advance Technology)
(6+6) Two power connector.
Motherboard sensing circuit absent Automatic shutdown not available
ATX (Advance Technology Extended)
20 or 20+4 Pin power connector
Mother board sensing circuit available Automatic shutdown available
PS_ON activated by pressing and releasing the power button while the power supply is in standby mode.
Activating /PS_ON turns on the power supply.
Pin 9 (standby) supply 5V even when SMPS is turned off. Pin 14 goes from 0 to 3.7 when SMPS switch is turned on.
Shorting pin 14 (/PS_ON Green) to GND (COM Black) causes power supply to switch ON, means smps ok