Help needed desperately re- Power connector to motherboard

[screwball]

I have got up early to start building a newer computer. Hit problem in first 10 minutes. Screwed in m/Board. First connection power! I have a brand new PSU, the Atx Power has 20 pins (various rounds and squares) on the board it has 24 The board is an ATX so I dont understand. The board is a Intel Pentium4  925x. If I insert the lead into the board block starting at one end it fits perfectly as the shapes match. At the other end it won' t (of course). But if the various powers that are given are wrong, I will blow the board or other stuff - where do I go from here??
Gratefull for any guidance
Kevin

[Joe_Flanagan]

It's probably an older PS if it has a 20-pin on it.
What is the make/model of this PS ?

There's an outside chance that it is a 20+4 connector.
In this case the main connector (20) sisters with a specific 4-pin conn. to create a 24-pin. Check the docs.

If you would post your rig specs we can point you to a reliable power supply.

There are many junk power supplies that await the unsuspecting and when they fail, they can take other components with them.

[Dusty]

Here... Here is a write-up on the differences between ATX 12V Ver1.3 and ATX 12V Ver 2.0 power supplies.   If your psu does not have the extra 4-pin plug your system might work perfectly but .....  Then again you could use a 20 to 24 pin adaptor cable...   My choice would be to change the psu if 24 pins are not available...

Good luck

[screwball]

Thankyou for your time. It is a new 'Colors it'  550 watt Golden silent.
As previous post, the tower case is an ATX The board is an ATX Intel Pent4 925x temporarily to set up with just 612 mb ram

[contrex]

20 pins on the power connector from the PSU means that the PSU is ATX. There is a newer PSU standard called ATX-2 which has 24 pins. ATX-2 has the 20 regular ATX pins plus 4 extra pins to supply the extra power that certain processors and display cards need. These pins are added to one end of the connector, after the regular 20 pins of the ATX standard connector. In fact some suppliers describe an ATX-2 connector as "20 + 4" pin rather than "24 pin".

If your hardware specs call for an ATX PSU then an ATX-2 PSU will do the job. The 20 pin ATX plug will mate correctly with the first 20 pins of your motherboard power header. The voltages will be correct but you need the extra pins if (say) you had a dual core CPU or a SLI 6800 Ultra display card.

[screwball]

Contrex,
You are making noises that I really wanted to hear :-). Can I interpret them as follows? I can plug the power lead into the matching block (which matches perfectly), Leaving the other four open?  I thought myself this would be ok, but when I viewed the wiring diagram off the net http://www.pcguide.com/ref/power/sup/partsMotherboard-c.html
the various powers and grounds were completely different? Perhaps with the result of blowing the thing to bits.
Thanks again for your time

[contrex]

Screwball, in what way is the diagram different from what you have? Are you talking about the wire colours? Not all manufacturers follow these conventions.

Which diagram are you talking about?

[screwball]

If you have viewed the site previously posted, I believe I am correct in reading that on the 20 pin diagram, the pins are radicaly different from the 'corresponding' pins on the 24 block i.e. on one 3.3 on the other ground etc. Hang on, I've just looked again - kindly disregard this post!!

[contrex]

Hang on, I've just looked again - kindly disregard this post!!

Happens to  the best of us 

[screwball]

Thanks for your patience ! I gave wrong http! Correct one is *Blocked Russian URL*/Power/atxpower_pinout.shtml
In the diagrams the layout is similar, but on the 24 pin block, No. pin 18 is Black Ground - on the 20 pin block it is white 5v. Pin 19 is Black ground - on 20 block No.19 is Red 5V. Surely this will send 5v where it should be groung?? Forgive my pedanticness but I do not want to blow the board or somthing, I am treading on unknown ground.

[imanidiot]

hey guys don't mean to sound rude but there is no way u can use the power supply you have you are going to have to go to ur local pc store and ask them for a 20+4 pin power supply its as simple as that i had the same prob with mine so all i did was buy a new psu. c if even you can take ur old one back if it is brand new and get ur cash back to buy ur new one. and thats it!!! hope that helps

[contrex]

Yes, I agree that the pinouts in those diagrams are different, it's just that I keep finding information such as this

> If a mobo has an ATX2 connector, will an ATX PSU be ok or does the PSU have
> to be ATX2?

It should be OK if the PSU has a sufficiently generous +12V supply. Likewise a
PSU with an ATX2 connector will NOT be OK if the +12V isn't up to spec.

An ATX connector has the same pinout as the 20 pins at one end of the ATX2
connector, and they are intended to be compatible.

As always, a picture is worth a thousand words. Those diagrams that have worried you show the connector pin numbers in one long column, whereas the actual physical connectors are not like that.

If you look at this picture, you will see that the ATX and ATX-2 connectors have the pins arranged in two columns. They are numbered from the top left corner in these diagrams, pin 1 being square to ensure that the connector can only go one way.

Now, on the ATX power connector the left hand column runs from 1 to 10, and the right hand column runs from 11 to 20. On the ATX-2 connector, they run from 1 to 12 and 13 to 24.

So, pin 11 on an ATX connector corresponds to pin 13 on an ATX-2 connector. If you compare the left hand connector with the top 20 pins on the right hand one, you will see that the voltages match. COM and GROUND mean the same thing.



imanidiot, depends what CPU & GFX card he is using, whether the PSU will be OK. Whatever, it won't damage the board.

[screwball]

Ok  LETS GO FOR IT!!!!
Thankyou a million for all your help and interest. It's people like you make that life worthwhile.
Kind regards
Kevin