Hardware Reference
In-Depth Information
processors, but not the other way around. For example, you can install a processor with a PCG
specification of 05A in a motherboard with a PCG specification of 05B, but if you install a 05B
processor in a motherboard rated 05A, power problems will result. In other words, you can always
install a processor with lower power requirements in a higher-power-capable motherboard, but not
the other way around.
Although the PCG figures were specifically intended to apply to processors and motherboards, they
also can be used to specify minimum power supply requirements.
Table 18.13
shows the PCG
numbers and the power recommendations they prescribe. Intel stopped using the PCG numbers on
processors and motherboards introduced after 2009.
Table 18.13. Intel Platform Compatibility Guide (PCG) +12V Connector Power
Recommendations
Choosing a power supply with the required minimum output on the +12V connector helps to ensure
proper operation of the system.
Four-Pin +12V CPU Power Connector
To augment the supply of +12V power to the motherboard, Intel created a new ATX12V power
supply specification. This added a third power connector, called the
+12V connector
, specifically to
supply additional +12V power to the board. The 4-pin +12V power connector is specified for all
power supplies conforming to the ATX12V form factor and consists of a Molex Mini-Fit Jr.
connector housing with female terminals. For reference, the connector is Molex part number 39-01-
2040, and the terminals are part number 5556. This is the same style of connector as the ATX Main
power connector, except with fewer pins.
This connector has two +12V power pins, each rated for 8A total using standard terminals (or up to
11A each using HCS terminals). This allows for up to 16A or more of additional +12V current to the
motherboard, for a total of 22A of +12V when combined with the 20-pin main connector. The 4-pin
+12V connector is shown in
Figure 18.25
.
Figure 18.25. +12V 4-pin CPU power connector, side and terminal end view.
