Hardware Reference
In-Depth Information
This means the total power-handling capacity of this connector is only 58 watts. Drawing
more power than this maximum rating through the connector will cause it to overheat.
Combining the 20-pin main plus the auxiliary power connector would result in a maxim-
um power-delivery capability to the motherboard of 309 watts.
Few motherboards actually used this connector, and few power supplies included it. Gen-
erally, if a motherboard includes this connector, you need a power supply that has it as
well, but if the power supply includes the auxiliary connector but the motherboard does
not, it can be left unconnected.
Starting in 2000, both motherboards and power supplies began including a different addi-
tional connector that was a better solution than the auxiliary connector. The most recent
power supply form factor specifications have removed the auxiliary connector, rendering
it an obsolete standard in modern systems.
ATX12V 2.x 24-Pin Main Power Connector
Starting in June 2004, the PCI Express bus first appeared on motherboards. PCI Express
is a type of serial bus with standard slots having a single channel or lane of communica-
tions.Thesesingle-laneslotsarecalled
x1 slots
andaredesignedforperipheralcardssuch
as network cards, sound cards, and the like. PCI Express also includes a special higher-
bandwidth slot with 16 lanes (called an
x16 slot
), which is especially designed for use by
video cards. During development it was realized that PCI Express x16 video cards could
draw more power than what was allowed by the existing 20-pin main and 6-pin auxiliary
power supply connectors, especially when it came to +12V power.
The problem was that the 20-pin main connector had only a single +12V pin, but the new
video cards required more +12V power than a single pin could safely deliver. The +12V
connector that had already been added, as discussed in the next section, was specifically
for the CPU and was unavailable to other devices. Rather than add another supplemental
or auxiliary connector as it had done before, Intel eventually decided that it was finally
time to upgrade the main power connector to supply more power.
