Given that your system now boots slowly, I think that you should start fresh with a clean install of Windows.  If your Windows installer cannot see your internal drive, it's probably because you have RAID enabled. Windows installer doesn't include the Intel Rapid Storage Technology driver that is necessary for RAID. You would have to pause the Windows installer to insert that driver, such as in this process:[URL] An alternative is to enter BIOS and switch RAID to AHCI, then boot from your installer. With AHCI enabled, the Windows installer will see your drive. Whenever touching components or working inside a computer, wear a grounded wrist strap, also called anti-static wrist strap, ESD wrist strap, or ground bracelet. It's a cheap and sensible precaution. Rest the laptop on an anti-static mat or at least a reasonable alternative such as corrugated cardboard.
I am planning to remove and upgrade my old hdd in my inspiron 15 7559 because it is already slow when booting up but i don't know if my OS is embeded in my MoBo or should i transfer it to my new hdd first before removing and replacing my old hdd. any clue on what to do?
What should i do before i remove my old hdd in my Dell Inspiron 15 7559?