SATA Power Connector Question

  ykzn 13:23 07 Sep 06

Hi all!

I recently changed my PSU to Antec TruePower v2.0 ATX 12V.

This PSU has its own power connector for SATA HDD. That connector is with 5 wires.

Now I ha a power connector included with my motherboard. It is 4 pin to 15 pinconnector but it has only 4 wires at the SATA end.

So, I would like to know if it is even safe to connect the SATA HDD with the 5 wire power connector from the PSU?


  Gongoozler 16:34 07 Sep 06

Some SATA drives require a 3.3V supply which is provided by the additional cable from the PSU. This isn't available on the parallel ATA type connector and so a 4 conductor SATA connector will not be suitable for drives that need 3.3V. If the drive doesn't require 3.3V there won't be any internal connection to those pins so no harm will be done click here.

  ykzn 11:24 08 Sep 06

Hey Gongoozler,

Thanks for the info! According to you and your webpage, can it be said that even if I connect the connector from my PSU, there won't be any damage at all because the unused line is for 3.3V and is contrarily a lower voltage in the 5 wire connector from the PSU?


  Gongoozler 15:34 08 Sep 06

The SATA specification defines the allocation of each of the 15 pins in the connector.

Pins 1,2,3. - 3.3V
Pins 4,5,6. - 0V
Pins 7,8,9. - 5V
Pins 10,11,12. - 0V
Pins 13,14,15. - 12V

It's up to the drive manufacturers whether they use any of the power voltages. Parallel ATA only used the 5V, 0V and 12V supplies, so a parallel ATA to serial ATA converter can only use those. As far as I know, the 12V supply is only used to drive the motor. I don't know of any manufacturers who use the 3.3V supply. Modern switch mode power convertion techniques make conversion from one voltage to another quite simple and efficient, so the convenience of compatibility probably outweighs the small efficiency saving that would be made by using the 3.3V supply.
Any connection to pins 1, 2 and 3 other than for the purpose of using 3.3V would contravene the specification, and I think it is very unlikely that a manufacturer would contravene it.
This is the SATA interface specification click here

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