Hard disk not recognized?

I have a hard disk that I want to clone my C drive to, and I connected it via USB external; it showed up fine, I formatted it. However, since XP doesn't recognize boot drives through USB I wanted to attach it internally before I cloned my system drive over for when I do a boot test.

However, the drive that showed up just fine through USB isn't showing up when I plug it into the MB. It is recognized and is powering up, because when the system posts, the initial screen shows it is connected, and it gets warm after a few minutes, so it's working and the system can detect it, it is just not showing up in Windows.

I checked, and it's set to Slave.

What's the problem?

 

BlackScarletLove,

Can you see it in the BIOS? Is it SATA or IDE? Is it turned ON in the BIOS?

Can you see it in Disk Management?

 

go to control panel / administrative tools/ computer management / disk management
find your drive and put a drive letter to it. Once it has a drive letter it will show up under windows.