ThinkPad T420 Hard Drive Replacement

If the hard drive in your ThinkPad T420 has failed or you wish to install a larger or faster drive, this guide will show you how to replace the hard drive.

Guide notes

• This guide does not cover operating system installation.
  • While I make no promise or guarantee that I can help, if I know what you were running on the machine before the drive replacement, I may know where to locate an image of your OS.
• If you install an SSD or a thin Advanced Format (AF) drive, a 7mm->9.5mm drive spacer may be required. These are readily available online from sites like eBay if needed.
  • If you are installing a hard drive, cut the spacer based on the location of the breather hole. Heat WILL kill a traditional drive.
• ANY UNKNOWN HDP PASSWORDS MUST BE REMOVED BEFORE REPLACING THE DRIVE. IT WILL TRANSFER AS IT IS BACKED UP TO THE ATMEL CHIP ON THE BOARD!
• If possible, make a backup of your original drive and image it. This is optional, but it can help you recover if something goes wrong.
  • Note: This is not recommended for used systems. Reinstall from scratch and make a clean image from a fresh install.
• Once you are done with the old drive, if you do not need it, securely erase it.
  • Note: The procedure to wipe the old drive will vary by type. SSDs should be erased through a process known as "ATA Secure Erase" when possible to avoid putting wear on the SSD when it can be avoided. The drive will reset the encryption key, rendering the data unreadable.
    • NOTE: For HDDs with SED support, a similar process where you can reset the key can also be used. However, it generally requires the manufacturer tool as it was patched into the firmware (whereas it is natively supported on SSDs).
  • IMPORTANT: Legacy non-SED HDDs will still need to be wiped in a tool like DBAN, which takes hours or potentially days for larger drives, even with a 3-pass DoD wipe.