Is the following correct?

eSATA is the same as SATA, except that the cable plug has a slightly different shape, but as far as the electrical signal goes, it's the exact same thing. In theory, if you had a powered-on HDD enclosure with an eSATA port and a cable with an eSATA plug on one end and a SATA plug on the other end, you could connect this device directly to a SATA socket on the motherboard of a powered-on PC and it would work.

(Note: This is theoretical; I don't propose mucking about inside a powered-on PC.)

  • This is a very good question!
    – JL.
    Commented Nov 9, 2010 at 14:09
  • I'll be trying a practical setup to confirm this in next couple days. I have a 2.5 disk 'caddy' in a new computer case that has connectors for SATA power and SATA data. I'll be snaking an eSATA to SATA cable from an external port on the computer back into the computer case to reach the SATA data port. While power will come off the PSU.
    – Rolnik
    Commented Nov 22, 2010 at 16:14

3 Answers 3


Yes, from what I can tell, that is correct:

External SATA [eSATA] brings the SATA Hard Drive bus outside the PC chassis and allows external devices to be mounted to a SATA connection. The data cable runs out to a maximum of 6 feet. A shielded cable length of 3 feet or 6 feet is common for eSATA. The eSATA cable is shielded, but otherwise the same cable as used with SATA inside the PC.

  • 6
    Also note that eSATA has an I adapter and SATA has a L adapter. Not to be confused with SATA I (roman numeral I) which is SATA1 1.5 GBs.
    – Nate
    Commented Aug 26, 2009 at 14:48
  • but what about eSATA and SATA III (or I, or II) ? Commented Nov 12, 2014 at 2:40

Update: Here is a link to the SATA Standards Body's description of eSATA.

Here it mentions signal requirement changes in mid-2004:

Initially SATA was designed as an internal or inside-the-box interface technology, bringing improved performance and new features to internal PC or consumer storage. Creative designers quickly realized the innovative interface could reliably be expanded outside the PC, bringing the same performance and features to external storage needs instead of relying on USB or 1394 interfaces. Called external SATA or eSATA, customers can now utilize shielded cable lengths up to 2 meters outside the PC to take advantage of the benefits the SATA interface brings to storage. SATA is now out of the box as an external standard, with specifically defined cables, connectors, and signal requirements released as new standards in mid-2004. eSATA provides more performance than existing solutions and is hot pluggable.

I'll look at the specification to be certain (it might take a until lunch time), but my understanding is that the electrical specifications have changed slightly. Moving forward SATA controllers support eSATA as well. If you have an older chipset, them this is not necessarily the case.


Wikipedia ref External SATA on the SATA page.

Identical protocol and logical signaling (link/transport-layer and above), allowing native SATA devices to be deployed in external enclosures with minimal modification

The final eSATA specification features a specific connector designed for rough handling, similar to the regular SATA connector, but with reinforcements in both the male and female sides, inspired by the USB connector. eSATA resists inadvertent unplugging, and can withstand yanking or wiggling which would break a male SATA connector (the hard-drive or host adapter, usually fitted inside the computer). With an eSATA connector, considerably more force is needed to damage the connector, and if it does break it is likely to be the female side, on the cable itself, which is relatively easy to replace.

At the WiserGeek eSATA page

For desktop motherboards that don’t have an eSATA connector, a peripheral component interconnect (PCI) card can be purchased and installed in an available PCI slot that will provide an eSATA interface.

When purchasing an eSATA controller or bus card, be sure it supports the SATA standard required by your SATA hard drive(s). An eSATA controller made for SATA/150, for example, will not be able to support the faster transfer speeds of a SATA/300 hard drive.

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