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24 pin ATX power vs 20 pin

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March 16, 2005 12:59:14 AM

Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

I just ordered an Asus A8N-E motherboard that has a 24 pin power connector.

I would like to use an Antec Truepower 550 power supply but it has a 20 pin
power connector.

Does anyone know if this board work with this power supply? Or do I need a
20 to 24 pin adapter?

(I don't want to spend the money on a new 24 pin power supply)

Thanks,

Jim

More about : pin atx power pin

Anonymous
a b ) Power supply
a b V Motherboard
March 16, 2005 11:08:25 AM

Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

>I just ordered an Asus A8N-E motherboard that has a 24 pin power connector.
> I would like to use an Antec Truepower 550 power supply but it has a 20
> pin power connector.
> Does anyone know if this board work with this power supply? Or do I need a
> 20 to 24 pin adapter?
> (I don't want to spend the money on a new 24 pin power supply)

The 20-pin connector will work fine with that board
without an adapter. It's not recommended if you
will be using a high powered performance video
card, however.


---
Kevin Chalker, Owner KC COMPUTERS
E-mail: kc@kc-computers.com Web: www.kc-computers.com
Internet dealer since 1991!!! See WWW.RESELLERRATINGS.COM!!!
March 16, 2005 11:08:26 AM

Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

Kevin, thanks for the prompt answer to my question. When you say "high
powered performance video," would this include the Abit Radeon X600 XT 128MB
DDR PCI Express video card? My Antec 550 PS specification states that the
12V supply is capable of 24 amps. Do you think this would be adequate for
this card?

Thanks again,

Jim

"KC Computers" <kc@REMOVEkc-computers.com> wrote in message:

> The 20-pin connector will work fine with that board
> without an adapter. It's not recommended if you
> will be using a high powered performance video
> card, however.
Related resources
March 16, 2005 11:09:00 AM

Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

In article <ZPRZd.82958$vK5.4282@twister.nyroc.rr.com>, "KC Computers"
<kc@REMOVEkc-computers.com> wrote:

> >I just ordered an Asus A8N-E motherboard that has a 24 pin power connector.
> > I would like to use an Antec Truepower 550 power supply but it has a 20
> > pin power connector.
> > Does anyone know if this board work with this power supply? Or do I need a
> > 20 to 24 pin adapter?
> > (I don't want to spend the money on a new 24 pin power supply)
>
> The 20-pin connector will work fine with that board
> without an adapter. It's not recommended if you
> will be using a high powered performance video
> card, however.
>
>
> ---
> Kevin Chalker, Owner KC COMPUTERS
> E-mail: kc@kc-computers.com Web: www.kc-computers.com
> Internet dealer since 1991!!! See WWW.RESELLERRATINGS.COM!!!

And that is due to the 20 pin connector having only one +12V
pin, while the 24 pin connector has two +12V pins. A single
pin is rated for 6 amps, before it gets hot and potentially
melts the plastic around the pin. A high end video card could
draw 4.5A, and your fan headers draws a bit too. And depending on
whatever else Asus loads onto the +12V, there could be a slight
contribution as well. (Xbitlabs has articles, where they measure
video card current consumption, so you can sometimes find
numbers there.)

If you use some kind of adapter product, that converts a
20 pin to 24 pin, that really wouldn't help, as where the
20 pin connector plugs into the 20 to 24 pin adapter, the
same 6 amp limit would exist. (That means, there is still
a potential to melt the plastic, but on the power supply end of
the power chain.) If, on the other hand, the adapter consisted
of a disk drive connector plus a 20 pin ATX connector on the
source side, and a 24 pin connector on the destinaton side, then
both ends of the adapter have two +12V pins, and then nothing
can get damaged. (But I haven't seen any adapters designed
that way.)

old 20 pin cable 24 pin mobo
x (pin not fed)
PSU ----------------------------------x this pin fed
^
|
Potential hot spot will be here ---+
if more than 6 amps flows into mobo


20 pin to 24 pin adapter
+------------------x 24 pin mobo
PSU --- 20 pin ------------+------------------x two 12V pins
^
|
+--- Potential hot spot will be here as
all current flows through one pin

If I was designing an adapter, I'd want to combine a 4 pin
disk drive connector plus a 20 pin power on the left, to
feed a 24 pin power connector on the mobo on the right. I
haven't seen one for sale like this.

PSU --- 4 pin DD conn --+
+---+------------------x 24 pin mobo
PSU --- 20 pin -------------+------------------x two 12V pins

EATXPWR

Pin Signal Pin Signal
1 +3.3 VDC Orange 13 +3.3 VDC Orange
2 +3.3 VDC Orange 14 -12 VDC Blue
3 COM Black 15 COM Black
4 +5 VDC Red 16 PS_ON Green
5 COM Black 17 COM Black
6 +5 VDC Red 18 COM Black
7 COM Black 19 COM Black
8 PWR OK Gray 20 -5 V
9 5 VSB Purple 21 +5 VDC Red
10 +12V2 Yellow 22 +5 VDC Red
11 +12V2 Yellow 23 +5 VDC Red
12 +3.3 VDC Orange 24 COM Black

Pins 11,12,23,24 are the extra pins added to the 24 pin
connector, over and above the 20 pin connector. Pin 1 on
both connectors lines up. To make an adapter, a source
of a single +12V, a +5V pin, a +3.3V pin and a ground
return pin are needed. A disk drive connector can give
+12V, +5V, GND. The old style 1x6 Aux power connector
could be used to donate +3.3V. Only the +12V is immediately
critical, followed by the ground pin on pin 24. The +3.3 and
+5V likely have enough current already.

You could craft a good adapter, by taking a 20 pin to 24 pin
adapter, and a disk drive Y connector. That should give enough
materials to make an adapter that has two +12V pins on
the left, to feed the two +12V pins on the 24 pin connector.

Before spending the time on a project like that, it is best to
chase down the power consumption numbers for your video card
and for the fans fed off the same +12V supply. If the video card
happened to have a separate power connector, so much the better,
as that would really reduce the risk to the mobo power connector.

Is this likely to be a problem ? My guess would be not
too likely, unless the video card is really sensitive to
the quality of the +12V. (So, maybe it won't burn, but maybe
the voltage on the video card could be on the low side.) Asus
put an Ezplug on the A8N-SLI and I really like that concept,
as it would remove the risk entirely when using a 20 pin power
supply.

Something else I noticed, when reading the manual (and this
is for you dudes who buy stuff without reading the manual
first) - while the A8N-E mobo has a PCI-E x4 connector on
it, the tech writers use weasel words when they say
"1GB/sec _total bandwidth_". How I interpret that, is
512MB/sec up and 512MB/sec down, which means the slot only
has x2 wiring placed on an x4 connector.(Note that the weasels
couldn't just says "its a x2 slot - get over it".) Just in case
you have a x4 disk controller board that expects a full x4
rate, or that you care about such things.

I wondered about that connector when I first saw the board
specs, because it seemed like too much bandwidth for the
typical bus bridges used on desktop chipsets.

A sweet alternative, would be to use an SLI board, stick a
video card in one slot, in x8 mode, plus a disk controller
card in the second video slot (x8 mode, but only uses
x4 mode bandwidth). But I still haven't read whether there
are any restrictions on video slots being usable for
generic PCI-E plugin cards, so i don't know if this is a
viable option or not. It should work, but Nvidia controls
the chipset drivers...

Paul
March 17, 2005 2:25:37 PM

Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

On Wed, 16 Mar 2005 08:09:00 -0500, nospam@needed.com (Paul) wrote:

<snipped absolutely excellent info>

Thanks Paul!

Maybe you can clear up a mystery for mein that case :) 

I was using an Antec Truepower 550W p/s to power an Asus AN8 SLI mobo
with a couple of 6800 cards

After plugging everything in I still had need for one more Molex
connection on the mobo, to be sure that enough power was getting to
the SLI cards

I was using supplied converters from Molex to 6-pin PCIX (videocard
power sockets)

I had no plug left after hard drives connected and so on so I plugged
one of the hard drive power plugs that was part of a couple lashed
together to power two hard drives - bit of a stretch. When I plugged
it in there was the smell of doom :)  and I replaced both the p/s
(Noisetaker ATA2.0 600W) and mobo. No converters :) 

All the power plugs were inserted correctly so I'm left speculating
that the EZ-Power (or similar name) socket on the mobo caused a short
somewhere - but maybe you can explain it?

Just wondering mate, everything's running fine and dandy now
March 18, 2005 1:55:37 AM

Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

In article <bppi31h6nggbl549nv9f37k6s1s97n16a0@4ax.com>, Weaver
<dratI@forgot.com> wrote:

> On Wed, 16 Mar 2005 08:09:00 -0500, nospam@needed.com (Paul) wrote:
>
> <snipped absolutely excellent info>
>
> Thanks Paul!
>
> Maybe you can clear up a mystery for mein that case :) 
>
> I was using an Antec Truepower 550W p/s to power an Asus AN8 SLI mobo
> with a couple of 6800 cards
>
> After plugging everything in I still had need for one more Molex
> connection on the mobo, to be sure that enough power was getting to
> the SLI cards
>
> I was using supplied converters from Molex to 6-pin PCIX (videocard
> power sockets)
>
> I had no plug left after hard drives connected and so on so I plugged
> one of the hard drive power plugs that was part of a couple lashed
> together to power two hard drives - bit of a stretch. When I plugged
> it in there was the smell of doom :)  and I replaced both the p/s
> (Noisetaker ATA2.0 600W) and mobo. No converters :) 
>
> All the power plugs were inserted correctly so I'm left speculating
> that the EZ-Power (or similar name) socket on the mobo caused a short
> somewhere - but maybe you can explain it?
>
> Just wondering mate, everything's running fine and dandy now

Is it possible the converter was wired wrong ?

It could either be a power supply failure, or a wiring error has
resulted in an output being shorted. To figure out what happened,
would require a multimeter. You would need to switch on the
power supply (by connecting PS_ON# to an adjacent COM pin), and
then verifying the voltages on all the connectors. Next, you would
examine the converter wiring, to make sure the pins are in the
right holes. You could even plug the converter into the PSU, and
then measure the voltages at the end of the converter.

If you have ever worked making wire assemblies, you would realize
how error prone the work is. As a young engineer, I was annoyed to
find one day, that our local shop had assembled some cables wrong.
So, I decided to sit down and make sixteen of them myself. I was
being very careful (because being a smartass, I was out to prove
that they weren't that hard to make), and I managed to get one
of them wrong. From that day onward, I had a fresh respect for the
people who did the work, and all the correct ones they managed to
make :-)

Paul
March 21, 2005 3:29:06 PM

Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

On Thu, 17 Mar 2005 22:55:37 -0500, nospam@needed.com (Paul) wrote:

>So, I decided to sit down and make sixteen of them myself. I was
>being very careful (because being a smartass, I was out to prove
>that they weren't that hard to make), and I managed to get one
>of them wrong. From that day onward, I had a fresh respect for the
>people who did the work, and all the correct ones they managed to
>make :-)

Horses for courses yep. Like those guys who make the fishing flies :) 

Thanks again mate

I should have realised when the power converter plugs only fitted
loosely that something was going to happen - old engineer here and if
something bad can happen it usually does doesn't it :) 
!