Do i have to format the entire drive or just reinstall windows?There's no issue fundamentally. HDD rpm speed may vary but if same then performance should be no different.
However, just plugging the laptop's HDD without reinstalling Windows on the hardware it'll be running will cause all sorts of software and activation conflicts.
Reinstalling Windows will actually format the disk anyway so you may want to backup anything you want first.Do i have to format the entire drive or just reinstall windows?