Hardware Reference
In-Depth Information
There are adapters that can convert a 24-pin connector to a 20-pin type, and the other way
around,butsurprisinglytheseadaptersare
not
usuallynecessary.Thetruthisthatcompat-
ibility has been engineered into the connectors, power supplies, and motherboards from
the start.
If you look at the 24-pin main power connector diagram and compare it to the previous
20-pin design, you'll see that the extra 4 pins are all placed on one end of the connector
and all the other pins are defined the same as they were previously. The design of these
connectors is such that it allows an interesting bit of backward compatibility. The result is
that you can plug a 24-pin main connector directly into a motherboard that has a 20-pin
socket (and vice versa) without using an adapter! The trick is to position the connector
such that the 4 extra pins are empty. Depending on the latch design, the latch on the side
might not engage, but the connector will otherwise plug in and operate properly.
Figure 18.28
shows how you would connect a new power supply with a 24-pin connector
toamotherboardthathasonlya20-pinsocket.Theterminalsonthe24-pinconnectorthat
arehighlightedingraywouldplugdirectlyintothe20-pinsocket,whereasthewhitehigh-
lighted terminals would remain free and unconnected.
Figure 18.28
Connecting a 24-pin main power connector to a 20-pin motherboard socket.