Many people has asked this question and I am here to share a solution for the same. First of all I will like to inform you all that It is possible to migrate Windows 8 from HDD to SSD without installing it. Some people find it boring to do a fresh installation of Windows 8 on their newly bought SSD as it is a time-consuming process. On the other hand, some find it of no point to buy a new operating system when their current windows 8 system works without any issue. So people falling in my explained category can refer below steps for migrating windows 8 from their HDD to SSD without installing it.

Before proceeding with the migration you will have to install the migrating software. There are a couple of one’s out there like Paragon Migrate OS to SSD and AOMEI Partition Assistant. I will suggest you to download and install Partition Assistant Home Edition. It’s available for free so I don’t think anyone will be having a problem with it. Partition Assistant Home Edition is actually a professional partition manager but it has system migration feature as well. Paragon Migrate OS is also an excellent system migration tool but as it’s a paid version some people might not tend to use it. However, if anyone doesn’t have any issue in spending some bucks on Paragon Migrate OS, then they can surely give it a try. Once you have downloaded and installed your desired migrating software you can step ahead with further steps:

Steps: (For Partition Assistant Home Edition)
  1. Launch Partition Assistant and click on “Migrate OS to SSD or HDD" under “Wizards” on the main interface in the left pane
  2. Click on “Next” In the pop-up window, select unallocated space on SSD and click on “Next” in the next dialog box
  3. You can extend your system partition or change the location as well as the drive letter accordingly in the pop-up window
  4. Once you have completed all of the above steps, you can click on “Apply” and you are done.

Note – After completing the migrating process you will have to Enable AHCI mode for the SSD. Enabling AHCI mode will boost the SSD performance. You can enable it form the BIOS during Windows boot up but then some people have complained that their system used to crash after that. So ill suggest you to follow the below safe steps for enabling AHCI mode.
  1. Press windows key + R
  2. Type “regedit” without quotes, hit enter, select regedit.exe from the list and run the Registry Editor
  3. Navigate to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Servic es\Msahci and set the "Start" value to 0
  4. Once you have made the changes, reboot your system, go into the BIOS > Configuration and change the disk mode to "AHCI". Just make sure that you are saving the changes before leaving BIOS.
  5. When your system reboots it will detect the change and will load the disk drivers automatically. Later on you can install the latest driver of your motherboard to keep your system up to date.

In case anyone has any doubt regarding the steps explained above or if anyone faces and problem while carrying out above tasks then they can feel free to ask, best of luck guys.