I recently got a new hard drive and installed it into my computer. I upgraded to windows 7 on the new hard drive and not my old one because I am using 780gb of space on the old one and do not want to format it. However, now my computer only sees the new hard drive and not the old one. I went into device management and it's not there either. Does anyone know what I can do?
Does your old hardrive have an OS installed on it? If it does it needs to be reformatted before windows can accept it along with your new one. You may be able to bypass this by plugging in in via a USB adapter and transferring your data to the new one and then formatting the old one.
You should provide more info like: what drives, what mobo, how do you connect them to the system. Most important - do you see both drives in your BIOS?
Mobo is an 870A-G54 and no, I don't see the HD in the bios. If it helps, the old HD did have windows Vista on it while the new one has windows 7. If I need to format the old one, I will, it's just that the old one has over 780gb of data on it.
It doesn't sound good. However if it's not recognized in BIOS it's not something you can correct by formating. The BIOS should recognize the drive as an item on low level independently of the logical structure applied.
Try moving the drive to another port /like between SATA2 and SATA3/ and also try switching the controller to IDE mode, switch off the AHCI at least temporarily.
The fact that an OS is installed in the HDD is certainly meaningless as to whether you can access it through another OS or not. If it does not show up in BIOS, I would think you have something wrong with your installation. Double-check the cable connections, and check if your HDD is not connected to a disabled controller's SATA port. Other than that, as pepe2907 stated, changing the HDD controller's mode to AHCI may have an effect, but I think this wouldn't prevent it from showing up in BIOS.