Old ATX or new ATX 12V PSU needed?

  BobG65 19:37 12 May 2010

My Computer based on an ASUS A7N8X-Deluxe MB is not starting or stopping properly. It takes many attempts to start and when shut down via windows or the power button it immediately restarts, I have to stop it with the mains switch.
I suspect the power supply but I cannot find out if a modern ATX 12V PSU will be compatible with the ATX spec of the MB.
I have checked the latest spec and find most PSUs have a power input to MB plug that offers 20 and 24 ways, 20 ways would suite the MB but my original PSU (Antec TruePower 430W) has a -5v supply on pin 18 (white wire) ATX 12V versions do not have this rail. Will the MB work without -5v? Does anyone know what it did on older MBs.

Many thanks if you can help


  BobG65 11:29 13 May 2010

Any ideas???

  chub_tor 11:43 13 May 2010

If you take a look at this page

click here

particularly the section lower down marked ATX12V 1.2 you will see the statement "A relatively minor revision from January 2002. The only significant change was that the ?5 V rail was no longer required (it became optional). This voltage was very rarely used, only on some old systems with some ISA add-on cards".

So if you do not have any ISA add-on cards included in your system it would seem possible (indeed probable) that a new ATX power supply would work for you.

Best bet would be to try and borrow one from a friend before buying one.

  northumbria61 11:52 13 May 2010

There is an interesting article here that MAY help -

Two paragraphs contain the following information in the below LINK

"I think the only difference is the 20 pin is changed to a 24 pin connector. They state on the link that you provided that the 24 pin connector is 20 pin compatible. Additionally, you can get a 24 pin to 20 pin adapter.

Assuming the TX-750 doesn't have the ATX 24 pin plug with the last 4 pins removable, which might be the case then use this ATX 24-pin to 20-pin Adapter Cable. It appears that they are out of stock, but you get the idea. I can't think of any other reason it won't work.

click here

  BobG65 18:02 14 May 2010

Many thanks to you both.

Combining the info in both links tells me the MB is going to be compatible with a modern PSU. I've gone ahead and ordered another Antec, the TruePower New 650w modular. It's way overpowered but it will allow future upgrades.

Thanks once again for your help.

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