what is the purpose of the 4 pin output from 350W power supply?

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totod

Bought a new case and there is an extra (haven't seen before) 4 pin
square connector comes out from the PSU. What's the purpose of this?

thanks
 
Bought a new case and there is an extra (haven't seen before) 4 pin
square connector comes out from the PSU. What's the purpose of this?

thanks
Click to expand...

Additional power supply for Pentium 4 processors, implemented by the
majority of good motherboard manufacturers.
 
ElJerid said:
<totod> wrote in message news:[email protected]...

Additional power supply for Pentium 4 processors, implemented by the
majority of good motherboard manufacturers.
Click to expand...
Its called ATX12V connector and many Athlon mobos now require it too.
 
Additional power supply for Pentium 4 processors, implemented by the
majority of good motherboard manufacturers.
Click to expand...

It really has nothing to do with "good", junk boards have them as
well, but some very good boards don't... excepting of course P4
boards, which always have them not as a technical requirement but to
avoid pissing off Intel by following their spec.


Dave
 
Probably +12 volts for a Pentium 4. The 12 volts goes to a switching regulator that converts it to high current at the low processor voltage. If you don't have a P4 you can use it for something else e.g. fans.
 
totod said:
Bought a new case and there is an extra (haven't seen before) 4 pin
square connector comes out from the PSU. What's the purpose of this?
Click to expand...

It provides extra amp capacity for the 12V power to the motherboard
because the 20-pin power connector has only a single 12V wire
(yellow), and a single wire can reliably provide only about 6 amps
without excessive voltage drop and heating at its connector. Things
like the CPU, DDR memory, and some AGP and PCI cards don't run
directly from the voltages provided by the power supply (3.3V, 5V,
12V, -12V, -5V) but instead from voltage regulators built into the
motherboard. They take higher voltages from the power supply and
convert them to lower voltages, and in the past these regulators were
fed from the 5V output, but fast CPUs draw so much power that the 4-5
red 5V wires (5 if the motherboard uses the extra 6-pin power
connector) may not be adequate, and using the 12V output allows
12/5ths as much power to be delivered reliably per wire.

You should use a power supply with a square 4-pin connector if your
motherboard has a matching connector because otherwise CPU voltage may
be too low or the 20-pin power connector overheat and melt slightly.
 
do_not_spam_me said:
totod <> wrote in message


It provides extra amp capacity for the 12V power to the motherboard
because the 20-pin power connector has only a single 12V wire
(yellow), and a single wire can reliably provide only about 6 amps
without excessive voltage drop and heating at its connector. Things
like the CPU, DDR memory, and some AGP and PCI cards don't run
directly from the voltages provided by the power supply (3.3V, 5V,
12V, -12V, -5V) but instead from voltage regulators built into the
motherboard. They take higher voltages from the power supply and
convert them to lower voltages, and in the past these regulators were
fed from the 5V output, but fast CPUs draw so much power that the 4-5
red 5V wires (5 if the motherboard uses the extra 6-pin power
connector) may not be adequate, and using the 12V output allows
12/5ths as much power to be delivered reliably per wire.

You should use a power supply with a square 4-pin connector if your
motherboard has a matching connector because otherwise CPU voltage may
be too low or the 20-pin power connector overheat and melt slightly.
Click to expand...

Good answer. All this "P4 boards" business gets a little annoying. OK, Intel
may have bought in the spec but all the nForce2 boards I've been working
with recently have the socket and won't run without the plug inserted.
(Well, I only tried one without the plug).
 
Good answer. All this "P4 boards" business gets a little annoying. OK, Intel
may have bought in the spec but all the nForce2 boards I've been working
with recently have the socket and won't run without the plug inserted.
(Well, I only tried one without the plug).
Click to expand...

Although a seemingly random selection of Athlon boards in the past,
prior to nForce2 chipset, used the 12V 4-pin connector, the nForce2
chipset boards were the first to see a very large percentage, probably
a majority, using that connector. Even so, one of the most popular
nForce2 boards, the Asus A7N8X, does not use it, still uses 5V for
CPU.


Dave
 
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