Whats the deal with 24pin ATX PSU connectors

[Pete]

I have just bought a Ultra Xconnect power supply 400watts to use in
conjunction with a AMD 3500+ and skt 939 board.

Here it is:
http://www.ultraproducts.com/product_details.php?cPath=42&pPath=296&productID=304

It says it supports Pentium 4 and AMD CPUs and meets ATX version 2.03 and
ATX 12V version 1.2 specification.

When I bought it I thought it was the dogs bollocks but now I see
motherboards with 24 pin PSU connectors and wonder what's going on.


Have I bought a lemon? Is it out of date? Has the ATX spec moved on?

Can you plug a 20pin ATX connector from the power supply onto a 24pin
connector on the motherboard and then use a 4 pin lead for the remaining 4
pins or would I need a convertor?


The motherboard I want to use it with has the following connectors:

24-pin ATX Power connector
4-pin ATX 12V Power connector

Would I need to buy extra cables / convertors to use it with this board?

Thanks

Pete

 

[John McGaw]

I have just bought a Ultra Xconnect power supply 400watts to use in
conjunction with a AMD 3500+ and skt 939 board.

Here it is:
http://www.ultraproducts.com/product_details.php?cPath=42&pPath=296&productID=304

It says it supports Pentium 4 and AMD CPUs and meets ATX version 2.03 and
ATX 12V version 1.2 specification.

When I bought it I thought it was the dogs bollocks but now I see
motherboards with 24 pin PSU connectors and wonder what's going on.


Have I bought a lemon? Is it out of date? Has the ATX spec moved on?

Can you plug a 20pin ATX connector from the power supply onto a 24pin
connector on the motherboard and then use a 4 pin lead for the remaining 4
pins or would I need a convertor?


The motherboard I want to use it with has the following connectors:

24-pin ATX Power connector
4-pin ATX 12V Power connector

Would I need to buy extra cables / convertors to use it with this board?

Thanks

Pete

20 + 4 = 24, or so the manufacturer suggests. It appears that you are
expected to use the standard 20-pin cable plus the 4-pin "P4" connector
to do the job.

 

[Paul]

I have just bought a Ultra Xconnect power supply 400watts to use in
conjunction with a AMD 3500+ and skt 939 board.

Here it is:
http://www.ultraproducts.com/product_details.php?cPath=42&pPath=296&productID=304

It says it supports Pentium 4 and AMD CPUs and meets ATX version 2.03 and
ATX 12V version 1.2 specification.

When I bought it I thought it was the dogs bollocks but now I see
motherboards with 24 pin PSU connectors and wonder what's going on.


Have I bought a lemon? Is it out of date? Has the ATX spec moved on?

Can you plug a 20pin ATX connector from the power supply onto a 24pin
connector on the motherboard and then use a 4 pin lead for the remaining 4
pins or would I need a convertor?


The motherboard I want to use it with has the following connectors:

24-pin ATX Power connector
4-pin ATX 12V Power connector

Would I need to buy extra cables / convertors to use it with this board?

Thanks

Pete

<----- ATX 2.0+ main connector -----> <--- ATX previous versions --->

Pin Signal Color Pin Signal Color Pin Signal Color Pin Signal Color
1 +3.3VDC Orange 13 +3.3VDC Orange 1 +3.3VDC Orange 11 +3.3VDC Orange
2 +3.3VDC Orange 14 -12VDC Blue 2 +3.3VDC Orange 12 -12VDC Blue
3 COM Black 15 COM Black 3 COM Black 13 COM Black
4 +5VDC Red 16 PS_ON# Green 4 +5VDC Red 14 PS_ON# Green
5 COM Black 17 COM Black 5 COM Black 15 COM Black
6 +5VDC Red 18 COM Black 6 +5VDC Red 16 COM Black
7 COM Black 19 COM Black 7 COM Black 17 COM Black
8 PWR_OK Gray 20 Reserved N/C 8 PWR_OK Gray 18 Reserved
N/C (-5V)
9 +5VSB Purple 21 +5VDC Red 9 +5VSB Purple 19 +5VDC Red
10 +12V1DC Yellow 22 +5VDC Red 10 +12VDC Yellow 20 +5VDC Red
11 +12V1DC Yellow 23 +5VDC Red
12 +3.3 VDC Orange 24 COM Black

<--- ATX 2.0+ 12V for proc ------> <--- ATX previous versions --->
Pin Signal Color Pin Signal Color Pin Signal Color Pin Signal Color
1 COM Black 3 +12V2DC Yellow/Black 1 COM Black 3 +12VDC Yellow
2 COM Black 4 +12V2DC Yellow/Black 2 COM Black 4 +12VDC Yellow

Changes:

1) -5V removed, prev supplies probably had it. Usually not an issue.
2) Four addition pins on main connector. Extra +3.3V, +5V, +12V, GND
Helps with PCI Express motherboards. For SLI boards, 24 pin
recommended (to get two 6 amp pins to feed the two video cards via
PCI Express slot connectors). For single video card, 20 pin is
generally enough. 6600GT for example, draws 4 amps. Xbitlabs.com has
measured many cards. If in doubt, do a detailed calculation.
3) 12V output split into two separate 12V circuits.
No advantage to customer, due to need to allocate extra "slack" when buying.
Perhaps intended to meet IEC60950 ? (To limit max power per 12V output)
12V1 feeds disks and motherboard (and video card)
12V2 used exclusively for processor (in your computer, that would be 8.24A)

* 24 pin can plug to 20 pin mobo, as long as pins don't bump
20 pin can plug to 24 pin mobo (same pinout) - use the right holes.
Some 24 pin are detachable, into a 20 pin part and a detached 4 pin part.
At least one guy has managed to plug the detached 4 pin, into the processor
Vcore input. (I haven't checked to see how hard that is to do.)

PCI Express slots have 12V pins on them and allow up to 5 amps.
Video cards (not overclocked) seem to be designed to draw about 4 amps
or a tiny bit more, through the PCI Express x16 slot. The single 12V
wire on the 20 pin connector carries at least 6 amps, so using a
20 pin connector on a non-SLI board seems reasonable. The fan header
current also flows through the single 12V pin on the 20 pin connector.

Main connector rated for 6 amps per pin.
http://www.molex.com/cgi-bin/bv/molex/jsp/products/datasheet.jsp?ProductID=98716

12V processor power connect pins rated at 8 amps per pin.
http://www.molex.com/cgi-bin/bv/molex/jsp/products/datasheet.jsp?ProductID=76873

Molex disk drive connector rated at 8 amps per pin (based on assuming
a right angle PCB mount connector, and 18 gauge wire - Amp 82181 catalog)

Enjoy your new power supply. No need for adapters.

The Ultra you have selected, has 12V @ 16A. If you had an 89W AMD
processor, that is (89W/12V)/0.90 = 8.24A. A midrange video card like
6600GT is 4A. That is 12.24 amps so far. A disk drive idles at 0.5A.
A CDROM can draw 1.5A according to the rating on the label. Allocate
0.5A for some fans. We are now at 14.74 amps of 16A. Your new Ultra
is suitable for a midrange gamer with minimal storage devices. More
than 16 amps is required if your PC has more toys in it. For example,
if you bought an ATI X1900XTX, it draws 10 amps (part through the
PCI Express slot, part through the 2x3 PCI Express connector), and
you would need about 12V @ 23A to have a stable computer. So, enjoy
your new Ultra, but do not overload it.

HTH,
Paul

 

[Cuzman]

John McGaw wrote:

" 20 + 4 = 24, or so the manufacturer suggests. It appears that you are
expected to use the standard 20-pin cable plus the 4-pin "P4" connector
to do the job. "


I'd like to see you try that one.

A few years ago motherboards only needed a 20-pin connector. The 4-pin
12V connector then became necessary for the Pentium 4. AMD eventually
caught up with its use of the 4-pin connector, yet it is still often
known today as a "P4 connector". Then, with the introduction of
PCI-Express chipsets, motherboards began to need separation of the 12V
rails through the main connector, so a 24-pin connector was introduced
to replace the 20-pin one.

You will often see PSUs advertised as having a 20-pin and a 4-pin
connector, which usually means a 20-pin main connector and a 4-pin 12V
"P4" connector. You also see some advertised as having a 20+4-pin
connector. You can't take the 4-pin "P4" connector and fill up the
missing slots on a 24-pin socket. Not only will it not fit (unless
considerably forced), but you will invariably need to plug in the 4-pin
connector elsewhere on the motherboard anywhere.

When you see a PSU advertised as 20+4-pin, it usually means that it has
a snap-away connector for use with either a 20-pin or a 24-pin main
socket. The 4-pin part here is not the same as the 4-pin "P4"
connector. You can see one of these 20+4-pin connectors here:
http://www.highpowersupply.com/icon/20+4main2.jpg

This quide from November 2005 explains it all a bit further, but came
before the introduction of the new 8-pin 12V connector.
http://tomshardware.co.uk/2005/11/23/pc_interfaces_101uk/page19.html

Most motherboards will soon move on from the 4-pin 12V connector to the
new 8-pin 12V connector. Like many new motherboards, this Gigabyte
GA-965P-DQ6 will need both a 24-pin main connector and an 8-pin 12V
connector. http://www.hexus.net/content/item.php?item=6233&page=4

You can get 20-to-24-pin adapters and 4-to-8-pin adapters, but there is
no guarantee that either will be able to supply a stable draw along the
new rail splits.
http://www.newegg.com/Product/Product.asp?Item=N82E16812183045 Some
motherboards don't like them, so you are invariably better off with a
PSU that handles the relevant splits itself.

 

[Pete]

<----- ATX 2.0+ main connector -----> <--- ATX previous versions
--->

Pin Signal Color Pin Signal Color Pin Signal Color Pin
Signal Color 1 +3.3VDC Orange 13 +3.3VDC Orange 1 +3.3VDC Orange
11 +3.3VDC Orange 2 +3.3VDC Orange 14 -12VDC Blue 2 +3.3VDC
Orange 12 -12VDC Blue 3 COM Black 15 COM Black 3 COM
Black 13 COM Black 4 +5VDC Red 16 PS_ON# Green 4
+5VDC Red 14 PS_ON# Green 5 COM Black 17 COM Black
5 COM Black 15 COM Black 6 +5VDC Red 18 COM Black
6 +5VDC Red 16 COM Black 7 COM Black 19 COM Black
7 COM Black 17 COM Black 8 PWR_OK Gray 20 Reserved N/C
8 PWR_OK Gray 18 Reserved
N/C (-5V)
9 +5VSB Purple 21 +5VDC Red 9 +5VSB Purple 19 +5VDC
Red 10 +12V1DC Yellow 22 +5VDC Red 10 +12VDC Yellow 20
+5VDC Red 11 +12V1DC Yellow 23 +5VDC Red
12 +3.3 VDC Orange 24 COM Black

<--- ATX 2.0+ 12V for proc ------> <--- ATX previous versions
--->
Pin Signal Color Pin Signal Color Pin Signal Color Pin
Signal Color 1 COM Black 3 +12V2DC Yellow/Black 1 COM Black
3 +12VDC Yellow 2 COM Black 4 +12V2DC Yellow/Black 2 COM Black
4 +12VDC Yellow

Changes:

1) -5V removed, prev supplies probably had it. Usually not an issue.
2) Four addition pins on main connector. Extra +3.3V, +5V, +12V, GND
Helps with PCI Express motherboards. For SLI boards, 24 pin
recommended (to get two 6 amp pins to feed the two video cards via
PCI Express slot connectors). For single video card, 20 pin is
generally enough. 6600GT for example, draws 4 amps. Xbitlabs.com has
measured many cards. If in doubt, do a detailed calculation.
3) 12V output split into two separate 12V circuits.
No advantage to customer, due to need to allocate extra "slack"
when buying. Perhaps intended to meet IEC60950 ? (To limit max
power per 12V output) 12V1 feeds disks and motherboard (and video
card) 12V2 used exclusively for processor (in your computer, that
would be 8.24A)

* 24 pin can plug to 20 pin mobo, as long as pins don't bump
20 pin can plug to 24 pin mobo (same pinout) - use the right holes.
Some 24 pin are detachable, into a 20 pin part and a detached 4 pin
part. At least one guy has managed to plug the detached 4 pin, into
the processor Vcore input. (I haven't checked to see how hard that
is to do.)

PCI Express slots have 12V pins on them and allow up to 5 amps.
Video cards (not overclocked) seem to be designed to draw about 4 amps
or a tiny bit more, through the PCI Express x16 slot. The single 12V
wire on the 20 pin connector carries at least 6 amps, so using a
20 pin connector on a non-SLI board seems reasonable. The fan header
current also flows through the single 12V pin on the 20 pin connector.

Main connector rated for 6 amps per pin.
http://www.molex.com/cgi-bin/bv/molex/jsp/products/datasheet.jsp?ProductID=98716

12V processor power connect pins rated at 8 amps per pin.
http://www.molex.com/cgi-bin/bv/molex/jsp/products/datasheet.jsp?ProductID=76873

Molex disk drive connector rated at 8 amps per pin (based on assuming
a right angle PCB mount connector, and 18 gauge wire - Amp 82181
catalog)

Enjoy your new power supply. No need for adapters.

The Ultra you have selected, has 12V @ 16A. If you had an 89W AMD
processor, that is (89W/12V)/0.90 = 8.24A. A midrange video card like
6600GT is 4A. That is 12.24 amps so far. A disk drive idles at 0.5A.
A CDROM can draw 1.5A according to the rating on the label. Allocate
0.5A for some fans. We are now at 14.74 amps of 16A. Your new Ultra
is suitable for a midrange gamer with minimal storage devices. More
than 16 amps is required if your PC has more toys in it. For example,
if you bought an ATI X1900XTX, it draws 10 amps (part through the
PCI Express slot, part through the 2x3 PCI Express connector), and
you would need about 12V @ 23A to have a stable computer. So, enjoy
your new Ultra, but do not overload it.

HTH,
Paul

Thanks for the detailed reply Paul.

Just to confirm what you have said:

1. Plug the 20 pin ATX motherboard power cable into the 24pin socket on the
MB

then...

Sorry to be thick

Thanks

Pete

 

[Pete]

Thanks for the detailed reply Paul.

Just to confirm what you have said:

1. Plug the 20 pin ATX motherboard power cable into the 24pin socket
on the MB

then...

Sorry to be thick

Thanks

Pete

Sorry Paul, I just noticed that the spec on the side of the box is different
to the spec on their website.

This is what it says on the box, is this better for me or worse?

Thanks

Pete

+3.3VDC=16A
+5vDC=30A
+12vdc=19A 228W
-12vdc=0.6A
-5vdc=0.6A
+5vsb=2.0A






+3.3V

AC INPUT
115V/230V 10A/6A 60/50Hz
DC OUTPUT
+3.3V
+5V
+12V
-12V
-5V
+5VSB
500W
Max
Combined
Watts
28A
30A
34A
0.8A
0.3A
2A
500W

 

[John McGaw]

John McGaw wrote:

" 20 + 4 = 24, or so the manufacturer suggests. It appears that you are
expected to use the standard 20-pin cable plus the 4-pin "P4" connector
to do the job. "


I'd like to see you try that one.

A few years ago motherboards only needed a 20-pin connector. The 4-pin
12V connector then became necessary for the Pentium 4. AMD eventually
caught up with its use of the 4-pin connector, yet it is still often
known today as a "P4 connector". Then, with the introduction of
PCI-Express chipsets, motherboards began to need separation of the 12V
rails through the main connector, so a 24-pin connector was introduced
to replace the 20-pin one.

You will often see PSUs advertised as having a 20-pin and a 4-pin
connector, which usually means a 20-pin main connector and a 4-pin 12V
"P4" connector. You also see some advertised as having a 20+4-pin
connector. You can't take the 4-pin "P4" connector and fill up the
missing slots on a 24-pin socket. Not only will it not fit (unless
considerably forced), but you will invariably need to plug in the 4-pin
connector elsewhere on the motherboard anywhere.

When you see a PSU advertised as 20+4-pin, it usually means that it has
a snap-away connector for use with either a 20-pin or a 24-pin main
socket. The 4-pin part here is not the same as the 4-pin "P4"
connector. You can see one of these 20+4-pin connectors here:
http://www.highpowersupply.com/icon/20+4main2.jpg

This quide from November 2005 explains it all a bit further, but came
before the introduction of the new 8-pin 12V connector.
http://tomshardware.co.uk/2005/11/23/pc_interfaces_101uk/page19.html

Most motherboards will soon move on from the 4-pin 12V connector to the
new 8-pin 12V connector. Like many new motherboards, this Gigabyte
GA-965P-DQ6 will need both a 24-pin main connector and an 8-pin 12V
connector. http://www.hexus.net/content/item.php?item=6233&page=4

You can get 20-to-24-pin adapters and 4-to-8-pin adapters, but there is
no guarantee that either will be able to supply a stable draw along the
new rail splits.
http://www.newegg.com/Product/Product.asp?Item=N82E16812183045 Some
motherboards don't like them, so you are invariably better off with a
PSU that handles the relevant splits itself.

Yes. You are right. I went back and looked at the actual power supply in
question and see that what I took as the "snap on" connector clearly
isn't. Oh well, that is what happens when I jump in...

I guess that in this case one of the 20 -> 24 adapters might be the next
logical thing for the OP to try if a new PS is not in the budget. I've
only used them twice, both times on modest MBs, and had no problems.

 

[kony]

I have just bought a Ultra Xconnect power supply 400watts to use in
conjunction with a AMD 3500+ and skt 939 board.

Here it is:
http://www.ultraproducts.com/product_details.php?cPath=42&pPath=296&productID=304

It says it supports Pentium 4 and AMD CPUs and meets ATX version 2.03 and
ATX 12V version 1.2 specification.

When I bought it I thought it was the dogs bollocks but now I see
motherboards with 24 pin PSU connectors and wonder what's going on.


Have I bought a lemon?

Yes, but it has nothing to do with above issue of 24 pins or
not. It's a lemon because it's a junk PSU dressed up with
frivolous things. This is also why many of them are about
$10 after rebate as recurring specials at Radio Shack,
etc... but are >=500 pseudo-watts instead of 400.

If your system has integrated video, a very low powered
card, and not too many hard drives, you may find the psu
acceptible for the described system. I tend to feel Paul's
itemization of power consumption may miss a larger issue,
that we'd have to assume the PSU was capable of sustaining
that output first, and I mean sustain long term rather than
the day (if that) some website reviews try to use when
qualifying PSU.

 

[Paul]

Sorry Paul, I just noticed that the spec on the side of the box is different
to the spec on their website.

This is what it says on the box, is this better for me or worse?

Thanks

Pete

+3.3VDC=16A
+5vDC=30A
+12vdc=19A 228W
-12vdc=0.6A
-5vdc=0.6A
+5vsb=2.0A






+3.3V

AC INPUT
115V/230V 10A/6A 60/50Hz
DC OUTPUT
+3.3V
+5V
+12V
-12V
-5V
+5VSB
500W
Max
Combined
Watts
28A
30A
34A
0.8A
0.3A
2A
500W

If the link in question is this one, the 34A rating on 12V is plenty.
Just plug it in and use it

http://www.ultraproducts.com/product_details.php?cPath=42&pPath=296&productID=298

HTH,
Paul

 

[Pete]

If the link in question is this one, the 34A rating on 12V is plenty.
Just plug it in and use it

http://www.ultraproducts.com/product_details.php?cPath=42&pPath=296&productID=298

HTH,
Paul

No, the link shows the 500watt psu, mine is the 400watt one but all the
specs on the site differ from those on my box, that's why I typed them in. R
the specs I listed OK?

Thanks

Pete

 

[Paul]

No, the link shows the 500watt psu, mine is the 400watt one but all the
specs on the site differ from those on my box, that's why I typed them in. R
the specs I listed OK?

Thanks

Pete

OK. You copied two chunks of text. You show this one, which looks
like it might be copied from the label:

+3.3VDC=16A
+5vDC=30A
+12vdc=19A 228W
-12vdc=0.6A
-5vdc=0.6A
+5vsb=2.0A

and then you show a second chunk of stuff, which looks like it is
a copy/paste from the web page for a _500W_ power supply. Notice
how the "500W" text string occurs twice here:

AC INPUT
115V/230V 10A/6A 60/50Hz
DC OUTPUT
+3.3V
+5V
+12V
-12V
-5V
+5VSB
500W
Max
Combined
Watts
28A
30A
34A
0.8A
0.3A
2A
500W

So while it looks to me like two power supply specifications, I
guess you're telling me to ignore the second, longer chunk of
text, and pay attention to the first chunk ?

In my original reply to you, the last paragraph in the reply,
attempted to show you that I need to know the hardware in the
box to work out the power. I still do not know what video card
you are using. I picked as an example card, since I don't know
your video card, the 6600GT, and demonstrated how to total
up a few current consumption numbers. My example calculation
showed 14.74 amps of load on the +12V. Since you are telling
me the label on the side of the supply shows 12V @ 19A , that
is enough for the _sample_ hardware configuration I made up.

Either provide a complete hardware inventory of your computer,
so I can work out the _real_ number, or continue to not supply
the information, and work it out for yourself. My guess right
now is, you have enough power, at least until you tell me
about the X1900XTX you just plugged in.

Paul