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Wierd Power Supply connector - what is it?

I had a power issue with an Acer PowerSV desktop, when I went to replace the PSU with one I had on the shelf it had a strange connector I had never seen before.

If you click on this link, it will take you to a motherboard diagram of the comptuer in question.  The connector is labeled "CN9" and the description in the table for that item is "12V port"


The funny thing is, when I disconnect that 12V port and power on the computer, the CPU fan runs, but the hard drive does not boot up and the monitor remains off - so it is a necessary connector.

What is a 12V port and is it common on new PSU's?  

FYI - the connector is square and has 4 holes in the end - two have yellow wires going to them and two have black wires going to them.

2 Solutions
That Cable is intended to Supply the Extra Power, needed for the ATX Boards in conjunction with the Main Power !

If your board has both, you must connect both !

" What is a 12V port and is it common on new PSU's?  " - All components on your system operate at 12 V, so Yes, it is very common that 12 V ports come with new PSU's :) !

Best Regards !
This is an EXTRA power supply connector for the motherboard, usually to supply extra power to the CPU.  Most PSUs have one such connector or the other but this is a bit non-standard.  You may need to get an adapter from one of your HDD connectors or another 12V connector on the PSU to plug into this connector.
lundcaAuthor Commented:
Found a good article on it:


Thanks gentlemen, I will split the points!
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Best Regards !
12VDC auxiliary power connector required for CPU.  All recent PSUs include that connector since it is required on P4 and newer Athlon 64 motherboards.

Provides additional 12V power to run CPU.
Thanks for the Points !

Glad I could help !

Best Regards !
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