Easy Power Supply question

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John Smith

I have an Antec Power Unit and this seems to be running my pc ok via the
20-pin Main Power Connector.
However I've just noticed the Power Unit has two additional unused
connectors....

a 6-pin AUX Power Connector, and
a 4-pin +12v Power Connector

I have today plugged into the mobo the 4-pin Connector without apparent
improvement or any disadvantage..but can't see a place on my Abit mobo where
a 6-pin could be connected.

So the question is...what is the purpose of these two connectors?

Thanks.
ps Keep any answers as un-electrically technical as poss :-)
 
"John Smith" said:
I have an Antec Power Unit and this seems to be running my pc ok via the
20-pin Main Power Connector.
However I've just noticed the Power Unit has two additional unused
connectors....

a 6-pin AUX Power Connector, and
a 4-pin +12v Power Connector

I have today plugged into the mobo the 4-pin Connector without apparent
improvement or any disadvantage..but can't see a place on my Abit mobo where
a 6-pin could be connected.

So the question is...what is the purpose of these two connectors?

Thanks.
ps Keep any answers as un-electrically technical as poss :-)
Click to expand...

In electricity, there is a thing called amperage capacity, and
that term is sometimes shortened to "ampacity". Basically, it is
a matter of making room for electricity to flow, without stuff
getting too hot.

Think about the electrical wiring in your house for a moment.
The kettle and toaster, have thicker wires on them, than the
lamp in your study. Thicker wire is used to carry heavier currents,
without the wire becoming too hot.

There are two ways to make a thicker wire. The obvious way,
is to pack more strands into one cable (duh). Another way
(which is not used for house wiring), is to run two wires from
the same source to the same destination. That allows more current
to be carried safely.

Your ATX power supply has several kinds of amperage limits. One
limit, is the connector pins used. There are limits as to how
much current each pin can carry. The wires can generally take
more amps than the pins can, so the pins are a limit. You don't
want the pins to get hot, because they can melt the plastic.

The ATX main power connector already has multiple +5 and +3.3V
pins and wires. There was a time, when PC designers thought even
more +5 and +3.3V would be drawn, so they asked the power supply
companies to add a six pin AUX connector. A motherboard designer
would only add that 1x6 connector to the motherboard, if it was
felt that room for the additional current was necessary. (Connectors
cost money, so they don't slap them down for no reason.)

The era of needing extra +5 and +3.3V is past. So the Aux
connector has been removed from a lot of new supplies, and you
won't likely see it on a desktop motherboard.

The +12V 2x2 square connector has a similar history. At one
time, the main connector had enough room for the current on
the +12V. Now that +12V is used to power the conversion circuit
that feeds the processor, additional current is required. A
130W P4 processor would need more than 10 amps from +12V, so
they needed more wire to carry the current. That led to the
introduction of the 2x2 12V connector. For the majority of
P4 or Athlon64 motherboards today, that connector is mandatory.

So when you find a connector on a motherboard, it is there for
a reason. Best to connect it, if you've got it :-)

Paul
 
It is further alleged that on or about Sun, 7 May 2006 18:09:24 +0100,
in alt.comp.hardware.pc-homebuilt, the queezy keyboard of "John Smith"
<[email protected]> spewed the following:

|I have an Antec Power Unit and this seems to be running my pc ok via the
|20-pin Main Power Connector.
|However I've just noticed the Power Unit has two additional unused
|connectors....
|
|a 6-pin AUX Power Connector, and
|a 4-pin +12v Power Connector
|
|I have today plugged into the mobo the 4-pin Connector without apparent
|improvement or any disadvantage..but can't see a place on my Abit mobo where
|a 6-pin could be connected.
|
|So the question is...what is the purpose of these two connectors?
|
|Thanks.
|ps Keep any answers as un-electrically technical as poss :-)
|
The 6 pin plugs into a power hungry graphics card.
 
Paul said:
In electricity, there is a thing called amperage capacity, and
that term is sometimes shortened to "ampacity". Basically, it is
a matter of making room for electricity to flow, without stuff
getting too hot.

Think about the electrical wiring in your house for a moment.
The kettle and toaster, have thicker wires on them, than the
lamp in your study. Thicker wire is used to carry heavier currents,
without the wire becoming too hot.

There are two ways to make a thicker wire. The obvious way,
is to pack more strands into one cable (duh). Another way
(which is not used for house wiring), is to run two wires from
the same source to the same destination. That allows more current
to be carried safely.

Your ATX power supply has several kinds of amperage limits. One
limit, is the connector pins used. There are limits as to how
much current each pin can carry. The wires can generally take
more amps than the pins can, so the pins are a limit. You don't
want the pins to get hot, because they can melt the plastic.

The ATX main power connector already has multiple +5 and +3.3V
pins and wires. There was a time, when PC designers thought even
more +5 and +3.3V would be drawn, so they asked the power supply
companies to add a six pin AUX connector. A motherboard designer
would only add that 1x6 connector to the motherboard, if it was
felt that room for the additional current was necessary. (Connectors
cost money, so they don't slap them down for no reason.)

The era of needing extra +5 and +3.3V is past. So the Aux
connector has been removed from a lot of new supplies, and you
won't likely see it on a desktop motherboard.

The +12V 2x2 square connector has a similar history. At one
time, the main connector had enough room for the current on
the +12V. Now that +12V is used to power the conversion circuit
that feeds the processor, additional current is required. A
130W P4 processor would need more than 10 amps from +12V, so
they needed more wire to carry the current. That led to the
introduction of the 2x2 12V connector. For the majority of
P4 or Athlon64 motherboards today, that connector is mandatory.

So when you find a connector on a motherboard, it is there for
a reason. Best to connect it, if you've got it :-)
Click to expand...
---------------------------
Excellent...TVM for the idiots guide :-)
Yes the system is an Athlon XP2500..and as I say I've now connected the 4pin
block as well as the 20pin.
One coincidental(?) thing is...we've been having unexplained irregular power
cuts at the house for some time now...and always as far as I recollect
whilst the pc was switched on...could the fact that I didn't have the 4 pin
connected be the cause by any chance?
Cheers, John
 
John said:
I have an Antec Power Unit and this seems to be running my pc ok via the
20-pin Main Power Connector.
However I've just noticed the Power Unit has two additional unused
connectors....

a 6-pin AUX Power Connector, and
a 4-pin +12v Power Connector

I have today plugged into the mobo the 4-pin Connector without apparent
improvement or any disadvantage..but can't see a place on my Abit mobo where
a 6-pin could be connected.

So the question is...what is the purpose of these two connectors?
Click to expand...

To fix the deficiencies of the original 20-pin connector, which was
designed back when CPUs and video cards drew much less power than some
draw now. A single wire and its connector can deliver only about 8A
before it overheats or drops excessive voltage, so more wires are
needed to reliably deliver more amps. The single-row, 6-pin AUX
connector was introduced when AMD processors became power hogs. The
4-pin +12V connector was introduced when Intel came out with the
Pentium 4 and decided it was good to power CPUs from the +12V instead
of the +5V (a voltage regulator built into the motherboard converts
these voltages to the lower ones used by CPUs) since that would require
only 5/12ths the amps for the same amount of power (watts = amps X
volts), but the 20-pin connector had only 1 +12V wire (yellow). Then
when video cards started consuming more amps than the power cables and
bus connectors could handle, those cards got their own power
connectors, first with disk drive power cables, now with dual-row,
6-pin SLi connectors.

Use the extra connectors if your motherboard or video card need them or
your 20-pin connector may overheat its plastic or burn its pins.
 
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