Creating an external hard drive out of an old internal HDD is a good idea
QUESTION My PC's motherboard died, but I rescued the hard drive before getting rid of it. I put the drive into a caddy and tried to format it. In the old PC the drive used the letter C, which is also used by the main hard drive in my new PC. I was worried that using two drives with the letter C would cause problems, so I cancelled the formatting and attempted to assign a new drive letter in Disk Management. I don't appear to have done so successfully, though, since the drive letter flashes up intermittently. Is there anything I can do to format this drive? Dangerus1
HELPROOM ANSWER You seem to be following the right steps to resolve the issue, but it sounds as though there may be a problem with the drive enclosure. We're not sure what you mean when you say “the letter flashes up intermittently”; it could be that the drive enclosure isn't receiving enough power via the USB port and is repeatedly turning itself on and off.
Some caddies come with cables that have two USB connectors (known as Y-cables) to help get around this problem. If this is the case with yours, make sure both are plugged into your computer and, if possible, into USB ports located as far away from each other as possible.
Sometimes USB connectors on the front of a PC don't offer as much power as those at the back, so it's worth connecting the caddy to a rear port. If USB 3.0 ports are available, these often provide more power.
If none of these solutions work then you may need an external power supply for your caddy – some support these; others don't. If yours doesn't, then perhaps try an external drive enclosure that comes with a plug-in power adaptor.
If you can, try the enclosure on a different computer to see if it works more reliably there – this would also point to a power supply issue.
Once the external drive is working correctly, you should be able to delete all partitions from the external drive using Windows Disk Management. Your boot disk will probably show up as Disk 0, with the external drive appearing as something else. You should be able to correctly distinguish between the old and new hard drives by checking their capacities (assuming they are not identical).
After you've deleted all the partitions from the drive, you should be able to format it and use it as you wish.