Processor Configurations
12 Design Guide
2.2 High End Desktop Market Processor
Considerations
The High End Desktop market requires power supplies with higher power levels than
the mainstream market. Sometimes the EPS12V specification is referenced for these
designs. The EPS12V specification is a power supply form factor for the server market.
Here in the Desktop Power Supply design guide we are including higher power levels to
incorporate these higher performance desktop computers.
2.2.1 Modular Power Supply Connectors
For power supplies to be made for multiple end user applications it is recommended to
use a modular design with multiple cable options for the end user to decide how they
want to use power. The CPU connectors on the motherboard are either a 4 pin (2x2) or
8 pin (2x4) connector, detailed in Section 4.2.2.5
+12 V Power Connector. The
graphics card connector is either a 6 pin (2x3) or 8 pin (2x4) connector detail in
Section 4.2.2.4 PCI-Express (PCI-E) Graphics Card Connector. Both of these
connectors use the 12V rail to power the component, but use different pin locations
and keying so they are not interchangeable. Therefore, a modular design is
recommended for multiple end user possibilities.
The end user might decide to use the power supply with a lower power or non-
overclocked CPU and multiple graphics cards in the system and need more power
cables for the graphics cards. Another option is to use a higher power CPU that might
be overclocked and require more power connectors and less graphics cards in that
system. The connectors on the power supply provide 12V power and then the end user
can decide which cable to plug in to provide 12V power in their computer.
Here are some example modular designs. The orange box in each picture shows that
the connector on the power supply that provides 12V power rails.
Based on the amount of current that is needed to support a specific current (power)
level the guideline to follow is 6-8 Amps per pin. This is based on 18 AWG wire and a
solid connector pin. Based on this recommendation, here is how this can be applied to
the CPU power connectors:
• 12-16A support for 2x2 (4pin) connector
• 18-24A support for 2x3 (6pin) connector
• 24-32A support for 2x4 (8pin) connector
This recommendation is based on common design practice. PSU and system designer
may design or use differently and should be responsible for designing the PSU to meet
all electrical, thermal, safety and reliability requirements based on the application of
the PSU.
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