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SATA and PATA are two different and incompatible disk drive interfaces. PATA's the old guard, but SATA's taking over. I'll look at the differences.

This “SATA” stuff is new to me. What does it mean? It's something about hard disk drives, I know, but I don't understand what. I went to get a new hard drive for my machine and the one that I wanted was SATA. But when I told the salesperson what computer I had, he said I didn't want it and instead, I needed something called PATA or IDE? I'm very confused.

Well, one part of this is easy: IDE and PATA are two names for the same thing.

The rest - well, the easy part is that SATA and PATA are two different ways of connecting a hard drive to your computer. Your computer will have one or the other and what you purchase must, in general, match.

When we go further, however, things start to get a little complex.

The Interface

SATA and PATA (aka IDE) are two different disk drive interfaces. By that I mean that the physical and electrical connection to a hard drive will use either a SATA or a PATA interface.

3.5 inch SATA (left) and PATA/IDE (right) drives
3.5 inch SATA (left) and PATA/IDE (right) drives

The picture above shows the physical difference: the SATA drive on the left is a pair of flat connectors - the larger one for power, then the smaller one for data. The PATA drive on the right uses the larger connector full of pins for data and the four-prong connector on the right for power.

“As for compatibility, there is none. SATA and PATA drives are completely incompatible at the interface.”

SATA is an acronym for Serial Advanced Technology Attachment, often shortened to Serial ATA. Serial refers to the fact that data is sent one bit at a time down a single connection in each direction. There's a separate connection for data going into and out from the device.

PATA is an acronym for Parallel Advanced Technology Attachment, often shortened to Parallel ATA. Parallel refers to the fact that data is sent 16 bits at a time through a single 16-bit connection that is used for data traveling in both directions.

While it might seem faster to send 16 bits at a time, the PATA actually transfers data more slowly for a variety of reasons. Current PATA interfaces can transfer at up to 133 megabytes per second, where as SATA interfaces can transmit up to 150, 300, or 600 megabytes per second depending on the version of the interface being used.

The History

PATA is the older interface. Originally known as IDE (Integrated Drive Electronics), it was the connection of choice not only for hard disks, but for floppy and optical (CD/DVD) disk drives as well.

In recent years, the PATA interface has been slowly disappearing. Most new machines today come with SATA hard disk drives and may use a PATA interface only for the optical drive. As expected, optical drives are now also becoming available with SATA interfaces, so we could soon see the end of the PATA interface completely.


As for compatibility, there is none. SATA and PATA drives are completely incompatible at the interface. They can certainly co-exist in a machine but only if that machine has both SATA and PATA interfaces.

If a computer has only one of the two styles of interface, then only drives compatible with that interface can be used.

What it all means

In practical terms, what this really means is simply that you need to know what you have when you replace a drive or get drive-related equipment.

When replacing the drive in your computer, you must know whether your computer uses a PATA or SATA interface and make sure to get a replacement that uses the same.

If you decide to take a hard drive and put it into an external disk enclosure, you'll need to know whether it's a PATA or SATA drive and get a compatible enclosure. It's not the actual enclosure that's different, but the small amount of circuitry included that physically connects to the drive to provide the USB interface.

Article C4968 - October 28, 2011 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

AG Wright
October 28, 2011 6:49 PM

It might be good to mention here that there are IDE and SATA controller cards if one or the other is needed in a computer that has a PCI slot that is empty.

Dave Smithson
October 29, 2011 1:34 AM

I have heard about solid state hard drives - as I understand it these are hard drives with no moving parts - but very fast - although limited in capacity...Have I heard wrong, and are these solid state drives SATA, PATA, or are they another thing altogether?...confused

Typically SSD's use a SATA inteface.
Mark J
October 29, 2011 3:33 AM

Solid state hard drives (SSDs) can come with any of the same interfaces as hard drives, and SATA is a very common SSD interface

Dave Smithson
October 29, 2011 4:06 AM

Thanks Mark J.

Ken B
October 29, 2011 8:08 AM

We often need to take a drive out of one system and temporarily attach it to another. (For example, saving documents from a non-bootable drive and moving them to a new system.)

In that case, there are adapters that include IDE, SATA, and "mini" IDE (ie: for 2-inch laptop drives) connectors at one end, and USB on the other. They come in handy if you need to do something like this more than once or twice.

October 31, 2011 6:57 PM

He must have been trying to replace the drive in a very old computer. I haven't seen a new computer sold with an IDE drive in years.

November 1, 2011 10:19 AM

You can buy an adapter to plug into a SATA drive to use it on a PATA PC and vice versa.

November 1, 2011 10:21 AM

Just to muddy the issue a bit, there are converters you can buy that attach to the back of an IDE drive to convert it to SATA. I've had mixed success with them but when they work they work great.

Less commonly nowadays, you can also get an expansion card that plugs into a PCI slot on the motherboard that adds IDE ports if your system doesn't come with them by default.

richard field
November 1, 2011 11:30 AM

Hi Leo, very important article for me. I have 3 small dell puters that need sata HDs. I have a box of PATA HD's. A puter guy told me all i need is interface adapters to get pata HD to connect to these puters. i got them and have them connected but when i try and install windows says there is no HD there. So was this guy wrong, and there is NO WAY i will ever be able to utilize these PATA HD in these DELL puters?

November 1, 2011 11:41 AM

I have an older gateway, and it had a 60GB IDE drive that went bad. I went to newegg and saw the newest best priced drive, and silly old me got it without a second thought.

Turns out my pc needed IDE, and not SATA, which is what I got. After a BIOS update and a 15$ converter, it worked fine.

Craig Fearing
November 1, 2011 1:50 PM

If you have an external "desktop" drive unit, it is fairly easy to remove the drive itself and use the interface with a different drive, even the smaller laptop drives, in order to recover data from a partially defective drive. This can also let you treat a drive that has been corrupted by various malware.

It could be useful to expand the article to include mention of esata -- a variation that complicates the situation a little further.

November 1, 2011 3:19 PM

Richard, sounds like you need a driver for your new interface adapter. Check the adapter's website for the version of Windows you're trying to load. During Windows install, you'll have the option to load the driver for your adapter.

Mark J
November 1, 2011 3:32 PM

If they won't work as primary drives, you can try and see if they work as secondary drives. If that doesn't work, they should be able to be used as external HDs with either a USB PATA enclosure or adapter plug.
Can I use the internal hard drives from an old machine as an external drive on a new one.

Bill Nelson
November 2, 2011 12:11 AM

My 6-year old Dell Dimension 9100 has two EIDE drives using RAID to get a grand total of ~30Gb. When I bought it, I figured I'd never fill them, but now I'm getting close. I've been thinking about replacing them with a single larger (1Tb?) drive, but most of what I see available are SATA drives. Apparently they're faster and I think I still have an open PCI slot. Do you think switching the drive to SATA with an appropriate interface, would be a good idea? I'm also wondering if these drives are nearing the end of their lives. If one goes, all data is lost - except for the images on external USB drives.

Depends on how long you plan to keep your computer. I don't recall ever seeing a IDE drive at the 1TB capacity, so if that's what you want then you might not have a choice. But to avoid problems I'd get a SATA interface and install that drive as a second drive, and continue booting form your IDE drive.
Bill Nelson
November 2, 2011 12:15 AM

After proofreading and hitting "submit," I didn't notice until posted - I now have slightly >300Gb; not 30Gb. Sorry!

November 2, 2011 4:55 AM

Very good description.
Thanks !

November 3, 2011 4:14 PM

Isn't that a SCSI drive on the right?


Carlos R Coquet
November 4, 2011 8:06 PM

Actually, they do sell adapters to change IDE to SATA and viceversa. Small PCB with IDE interface on one side and SATA on the other. Both for desktop and notebook computer drives. I carry one with me.

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