Hard Drive Power Requirements

[prolfe]

Hi everyone!
Do Hard drives use 12V, 5V, or both? Do they use one of them at boot and the other when they're operating? If they only use, say, 5V, what does the 12V line do? Or vice versa?

 

[JustysRule]

Of course they use the 12v, basically everything uses a 12v source besides mabye the floppy drive. The question is, does it use a 12v and a 5v source? there are four wires going into the plug, one of which is 12v +, 12v -, mabye the other two are 5v + and 5v - ?

 

[fishmahn]

The hard drive uses both. 12v for the drive motor and probably moving the r/w heads, 5v for the electronics. At least, that's how older hard drives worked. Don't see any reason for it to be different today.

 

[fishmahn]

Look at the wires going to a molex and you'll see that the wires are red, yellow and 2 black. One is +12v (red I think, but I'm not looking at one so it could be yellow), the other color is +5v, and the 2 black are grounds - one for 5v and one for 12v (the PSU label should tell you which for sure).

If you were to ground your +12v line to the -12v line, you'd have a net of 24v and likely blow your HDD motor.

Mike.

 

[tweebel]

Some new serial ATA disks also use the 3.3V. At least, that's what's in the ATX 2.0 standard.