Hardware Reference
In-Depth Information
Thismeansthetotalpower-handlingcapacityofthisconnectoris192wattsusingstandard
terminals,whichisavailable toandusedonlybytheprocessor.Drawingmorepowerthan
this maximum rating through the connector causes it to overheat, unless the HCS or Plus
HCS terminals are used.
Combining the 20-pin main plus the 4-pin +12V power connector results in a maximum
power-deliverycapabilitytothemotherboardof443watts(usingstandardterminals).The
important thing to note is that adding the +12V connector provides the capability to sup-
port power supplies of up to 500 watts or more without overloading and melting the con-
nectors.
Peripheral to 4-Pin +12V CPU Power Adapters
If you are installing a motherboard in a system that currently doesn't have the +12V con-
nection for the CPU voltage regulator, an easy solution
may
be available; however, there
are some caveats.
Power adapters are available that convert one of the extra peripheral power connectors
found in most systems to a +12V 4-pin type. The drawback to this is that there are two
+12V terminals in a +12V 4-pin connector, and only one +12V terminal in a peripheral
connector. If the adapter uses only a single peripheral connector to power both +12V pins
of the +12V connector, a serious power mismatch can result. Because the terminals in the
peripheral connector are only rated for 11A, and the two terminals in the +12V connect-
or are also rated for up to 11A each, drawing more than 11A total can result in melted
connectors at the peripheral connector end. This is below the peak power requirements
as recommended by the
Power Supply Design Guide for Desktop Platform Form Factors
(
www.formfactors.org
)
, meaning these adapters do not conform to the latest standards.
I did some calculations: Assuming a motherboard VRM (voltage regulator module) effi-
ciencyof80%,aCPUpowerdrawof105Wwouldjustaboutequal11A,theabsolutelim-
it of the peripheral connector terminal. Because most CPUs can intermittently draw more
than their nominal rating, I would hesitate to use one of these adapters on any processor
rated at more than 75 watts. An example of a peripheral to +12V adapter is shown in
Fig-
