No, can't see it in disk management in XP or 7. Disk unlocker didn't show anything. Could the MBR be affecting this new drive? I haven't used my XP hard drive in over a year, was thinking I could just reformat both drives and reinstall Windows 7. Still don't understand why it's not even showing in bios. Maybe something wrong with the drive? It is spinning and has good connection to the board, using all 4 sata ports now, all are enabled in bios. Running out of ideas lol. Do you think reformatting might do anything? Just low level format both, XP was the first OS, but xp 64 bit supported large drives like this I thought.