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Hard Drive Form Factors Explained

This is the first article in a series that will explain how hard drives work, why they fail and what you as users can do to protect your data. When looking at hard drives the first step is to identify what it’s form factor is. Simply put, the form factor is the size of the hard drive and how it connects to your computer.

The most common type of hard drive form factor is 3.5 inch for desktop disks. Laptop hard drives are almost alwas 2.5 inch form factor. Almost all computers manufactored today for consumers and small businesses have either IDE or SATA hard drives with a normal 3.5 or 2.5 inch form factor.

Why Is a 3.5 Inch Hard Drive Form Factor actually 4 inches wide

The 3.5 inch form factor doesn’t actually refer to the physical measurement of width or height of the drive, but refers to what the size of the bay is on the computer. Originally the 3.5 inch form factor was used in reference to the size of the PC’s floppy drive. Today hard drives are typically smaller than their counterparts from 5 years ago.

Watch the video below for a visual guide to common hard drive form factors:

[flv:hard-drive-recovery-form-factors-flv.flv 320 240]

Laptop hard drives are 2.5 inch form factors and like desktop disks, can be either IDE or SATA. The video above shows the difference between the cables and power connections on the two types of hard drives. Today there is also a significant difference in hard drive pricing when it comes to SATA and IDE. When looking at hard drive recovery, we don’t charge more for one or the other.


11 Responses to “Hard Drive Form Factors Explained”

  1. DTI Data Recovery October 9, 2008 3:36 pm #

    Yes, a hard drive adapter that converts SATA will work on either a 2.5 or 3.5 hard drive.

    3.5 and 2.5 IDE drive however, need a special adapter. We have a video that shows how to hook up and slave a laptop hard drive to a USB enclosure that explains how to use a 2.5 to 3.5 form factor adapter

  2. Dave October 9, 2008 3:23 pm #

    Cool so an adapter for SATA to IDE would work on 2.5 and 3.5 form factor drives?

  3. Danny Harris January 26, 2009 9:48 pm #

    I have a 750 gig maxtor external hd that is only a couple of months old and my toddler grand daughter accidently pulled it off my work table and it worked for a day or so but now all it will do is make a very low intermittent buzz, I was told by a friend who is a semi expert that the spindle motor is locked up. is this something that can be repaired and if so can you tell me aprox. what kind of charge I am looking at.
    there is only about a 100 gigs being used and its mostly photos with some photoshop documents.
    Thanks, Danny Harris

    • DTI Data Recovery January 27, 2009 4:43 pm #

      Danny, the best thing to do is give us a call at 727-345-9665 extension 203. Tell them you called from our blog and they will give you a discount : )

  4. sonny B April 27, 2009 11:40 pm #

    my old pc ‘s mother board dont work it dont even power up ,sometimes and shuts down whenever, I want toget the data off that hard is 3.5 ide I have the usb/ide adapter but where do I get the power from do I need another adapter from hard drive to ac power? then I should just plug in the usb to my new pc ?

  5. William S June 7, 2009 4:50 am #

    I’m convinced bearings are out of place in my motor. I’ve done extensive research in a considerable ammount of time (three days) and it is my understanding that this type of repair is the most costly due to the TEDIUM involved.
    Seagate 7200.10 320GB of which only about 30GB is needed.

    Please reason with me? I’m in a spot of bother here.

    William S
    Phildelphia Pa

  6. Gordon August 15, 2010 12:37 pm #

    What is the different between Seagate ST320005N1A1AS-RK and ST32000641AS

  7. Gordon August 15, 2010 12:44 pm #

    How do I know which Seagate model number is the newer one

    for example the Seagate from best-buy is ST320005N1A1AS-RK

    and from TigerDirect Seagate is ST32000641AS which one is this years model 2010

    • Jacqui Best August 20, 2010 12:11 pm #


      RK is for RETAIL hard drives for places like Bestbuy,CompuUsa,and Walmart

  8. GARRY February 6, 2011 6:21 am #



  1. » Blog Archive » Links for today - October 9, 2008

    […] Your hard drive got corrupted and you fear the possibility of losing your important data. Heres when data recovery can help you. Michael Stankard explains how hard drives work, why they fail and what you as users can do to protect your data. Read more […]

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