# Spec for power plug on SATA drives

**URL:** <https://boards.straightdope.com/t/spec-for-power-plug-on-sata-drives/920836>\
**Category:** Factual Questions\
**Created:** [September 17, 2020, 2:34pm UTC](https://boards.straightdope.com/t/spec-for-power-plug-on-sata-drives/920836 "2020-09-17T14:34:30Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\
**Post date:** [September 17, 2020, 2:34pm UTC](https://boards.straightdope.com/t/spec-for-power-plug-on-sata-drives/920836/1 "2020-09-17T14:34:31Z")

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There are several pins on the power connector for a SATA hard drive. Why so many?

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**Author:** ![Cleophus](https://avatars.discourse-cdn.com/v4/letter/c/a88e57/32.png) [@Cleophus](https://boards.straightdope.com/u/Cleophus)\
**Post date:** [September 17, 2020, 2:50pm UTC](https://boards.straightdope.com/t/spec-for-power-plug-on-sata-drives/920836/2 "2020-09-17T14:50:48Z")

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The main reason is to distribute current across multiple pins so as to keep within the allowable current for an individual pin. A “molex”-style pin can support more current than SATA edge pins so more are needed. Second, there is space for 12V, 5V, and 3.3V sources. Finally, two of the pins are dedicated to signaling purposes.

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**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\
**Post date:** [September 17, 2020, 3:18pm UTC](https://boards.straightdope.com/t/spec-for-power-plug-on-sata-drives/920836/3 "2020-09-17T15:18:46Z")

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> [@Cleophus](#):
>
> there is space for 12V, 5V, and 3.3V sources.

I am guessing that the motor and the controller all have different power needs. I hadn’t thought about that.

> [@Cleophus](#):
>
> two of the pins are dedicated to signaling purposes.

That was one of my guesses but I didn’t know what kind of signaling a power supply would do to a hard drive. (I am a curious guy but IANAEE.)

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**Author:** ![Didi44](https://avatars.discourse-cdn.com/v4/letter/d/e47c2d/32.png) [@Didi44](https://boards.straightdope.com/u/Didi44)\
**Post date:** [September 17, 2020, 5:06pm UTC](https://boards.straightdope.com/t/spec-for-power-plug-on-sata-drives/920836/4 "2020-09-17T17:06:00Z")

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There’s no motor. The head actuator is magnetically driven.

Here’s the SATA specs: [https://en.wikipedia.org/wiki/Serial\_ATA](https://en.wikipedia.org/wiki/Serial_ATA)

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**Author:** ![Cleophus](https://avatars.discourse-cdn.com/v4/letter/c/a88e57/32.png) [@Cleophus](https://boards.straightdope.com/u/Cleophus)\
**Post date:** [September 17, 2020, 5:50pm UTC](https://boards.straightdope.com/t/spec-for-power-plug-on-sata-drives/920836/5 "2020-09-17T17:50:18Z")

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> [@Didi44](#):
>
> There’s no motor. The head actuator is magnetically driven.

Of course there’s a motor, to make the disk spin.

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**Author:** ![Didi44](https://avatars.discourse-cdn.com/v4/letter/d/e47c2d/32.png) [@Didi44](https://boards.straightdope.com/u/Didi44)\
**Post date:** [September 18, 2020, 2:22am UTC](https://boards.straightdope.com/t/spec-for-power-plug-on-sata-drives/920836/6 "2020-09-18T02:22:26Z")

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Of course. I realized that a few hours after my post! 😊

My mind was on some other posts on Reddit where someone claimed the actuator had gears!