Hi i have just installed a 2nd hard drive to use as a backup the second drive is not a new one. I have put it to slave and left the main one as is. when i boot the pc its not showing in my computer. Ive looked in device manager and it says its there but i cant accsess it. ive checked bios and it also shows there. any help would be great.

Check the Disk Management.

Most likely it is unformatted or formatted to a file system unknown.

What is the File Format?

If you do not want the data then just go ahead and format it NTFS.

thanks ive done this and now all is ok.

Cool.

Let us know if we can help further in the future.