The Orange Wire on Modular SATA Power Connections

[BonzaiDuck]

I've observed a few things.

First, my parts locker contains quite a handful of Molex-to-SATA cable patches: you get them as accessories with any number of products, and I don't remember purchasing them separately.

Second, these Molex-to-SATA cables only feature the four wires used for a standard Molex power-connection string. I readily use them when I don't want to install another modular cable to my PSU, and need an SATA power plug when I have an unused Molex plug in the case.

Now I've undertaken a ridiculously simply modification of some USB external drive boxes to make them eSATA external drives. You can see my other recent thread here where I proposed the possibility, and shown it to be an apparent success. In order to power an SATA drive, I had to use one of those 6" Molex-to-SATA converter cables.

I have myriad modular cabling for some Antec PSUs which had either "gone South" or I don't plan on using further. I notice that these cables have a fifth orange wire running the length of the SATA cable through all the power connectors. A comparable cable with Molex plugs doesn't have this fifth wire. And as I said, the Molex-to-SATA patch cables don't have it.

What is the purpose of that fifth orange wire?

 

[Ig]

3.3v

I've never had a drive that needed it. Probably because molex-to-sata power adapters are so widespread. So to ensure compatibility they convert to 3.3v instead of requiring it at the power connector.

 

[Hellhammer]

It's a 3.3V rail (red is 5V and yellow is 12V, the black ones are just for grounding). In desktop environments it's not usually needed (all 2.5" and 3.5" drives take either 5V or 12V) but e.g. mSATA SSDs use the 3.3V rail, hence it's part of the SATA power spec. You shouldn't worry about it, though, you won't need it.

 

[BonzaiDuck]

It's a 3.3V rail (red is 5V and yellow is 12V, the black ones are just for grounding). In desktop environments it's not usually needed (all 2.5" and 3.5" drives take either 5V or 12V) but e.g. mSATA SSDs use the 3.3V rail, hence it's part of the SATA power spec. You shouldn't worry about it, though, you won't need it.

Thanks, both of you. Another area of my sparse familiarity -- mSATA. That all makes sense now.

I'm trying to decide which of my "IDE-to-USB" boxes to convert to eSATA, explained in another thread as current as this one. Seems reasonable to leave enough IDE-to-USB external boxes to use IDE drives that are 500GB and large enough to be useful. But I was also debating whether to simply connect the Molex plugs using the ubiquitous patch/converter cables, or just cut off the box's Molex plug and solder in an SATA plug cannibalized from those old Antec PSUs.

It amazes me that I post more and more threads and questions that may seem trivial, but I always learn something when I do.