I know these already.

1) In order for me to utilize a old Hard Drive into a new Mobo, I need to reformat the Hard drive first.

2) A Hard drive will not boot on a new MoBo because it would require the necesarry drivers to utilize the Mobo.

But here is my problem, I have a 10 year old Dell Optiplex 790 computer whose motherboard got roasted, literally. Having checked the hard disk for any defects, internally and extenally, and proved that the hard disk is working, my problem now is using the old hard drive. It has a software which we don't have the installer. I was tasked to boot up the old hard drive, but how do I do it?

EDIT: The new MoBo btw is Asus h110m-D 1151 socket, the OS would just be the same, Windows 7 32bit Pro edition.

  • Acronis Universal Restore can clone drives so they will boot on dissimilar hardware, assuming the newer hardware can actually run the older OS, but software recommendations are off-topic, so this can't be an answer. You really don't want to move the old drive itself; after 10 years it's well past its sell-by date. This also is dependent on how the software is licensed. If it's a simple serial code then it will work; if it's tied to the hardware you'll probably need to re-authorise. You will also need a new Windows license.
    – Tetsujin
    Nov 7 '17 at 8:11
  • 1
    I'd try fire it up in a VM - A VM can minimize your chances of not having appropriate drivers . Alternatively, you can buy a Dell Optiplex off EBAY for well less then $200. If a straight VM does not work, get an Optiplex, use Sysprep on it and then convert it to a VM. Alternatively, depending on the software, you may, of-course, be able to extract the key from it and get the install media off a torrent site.
    – davidgo
    Nov 7 '17 at 8:17
  • 1
    1)There is NO need to reformat a drive for usage in a new computers. Not unless you haave old 10MiB *(yes, mega, not hgiga) byte MFM drives. 2) The harddrive will probably boots just fine. Otoh the OS may hang during startup. You solve this by fixing the OS (e.g. sysprep windows before moving, ejnecting drivers etc). A whole format is NOT needed for this, though a clean start is often the easiest way out.
    – Hennes
    Nov 7 '17 at 12:26
  • 1) I think you do, If you would just slave a HD, you dont need to, but I would like to boot from the old one. 2) When I boot and access the command prompt, sysprep tells me there's a pending windows repair. I may have to add that I can't log in to the old computer because the unit itself is roasted (someone plugged the poor computer in a high power voltage socket for whatever reason, may his soul rest in peace)
    – Mr.J
    Nov 8 '17 at 0:23
  • I do agree with VM though... We will do this after we have the machine up and running, hopefully, using the new computer.
    – Mr.J
    Nov 8 '17 at 5:14

There's a lot of good answers here, most of which require both a second working PC and/or extra knowledge of the tools involved (i.e. virtualization of the old drive to backup files and move to a new Windows installation, or try to repair the system files somehow). This is the most risk-free and truly professional route that will guarantee you don't lose any data and has the best chances of success, so if you want to take the time to go that route I highly encourage it.

However, it sounds to me like you just have the new PC ready to go without a working hard drive so I'll give you my take on the simplest and quickest way to get the old drive back up and running based on my experience doing this same task too many times.

You have several paths to choose from, depending on your circumstances:

Route One: Repair System Files / Perform a Repair Install

PLEASE NOTE: This is the fastest solution, granted you must have the original Windows installation disk or have access to a copy of a 32-bit install disk from Microsoft. If you do not, please move on to the next section.

You can boot your new system up with the original installation disk and you can go right into a repair installation, which will preserve your data and just reinstall the Windows 7 system files which should reset any problems that are preventing the boot from completing at this point.

Here's a well-written repair guide from Lifewire which gives you detailed instructions for this fix:

Lifewire - Repair Windows 7 Installation

If that still doesn't work, here's a few alternative tricks from PC Gamer Magazine to fix the Windows boot:

PC Gamer - Fix Faulty Windows Installation Without Reformatting

And if still nothing seems to fix it, move down to Route Four for some other tools that should help fix the problem once and for all by using a system recovery disk.

Route Two: Download Install Media to DVD or USB Drive for Repair Installation

PLEASE NOTE: This step will require you to have access to another working PC for the download and creation of a new official disk image using official tools from Microsoft, and most importantly, this requires that you have access to your original Windows 7 product key. This WILL NOT WORK unless you have the key, and the one given by your manufacturer stuck on the case unfortunately WILL NOT WORK. If you don't have the product key, skip to the next route!

Go on over to Microsoft's website and you can download a new copy of the 32-bit Windows 7 install disk in ISO format which you can easily burn to a DVD or write to a bootable USB drive. You'll need to enter your product key to access the download.

Microsoft - Download Windows 7 Installation Disc

After you get the download completed, you'll want to use the media creation tool that Microsoft provides to burn the ISO to a DVD or create a bootable USB:

Microsoft - Windows USB/DVD Creation Tool

Finally, you can complete the Windows repair by using your new installation media and following the same instructions from the above Route One, or by clicking this link:

Lifewire - Repair Windows 7 Installation

Still not working? Move on down to Route Four for another method that should finally do the trick.

Route Three: Use Recovery Disk to Find the Windows Product Key, Repair Install Windows, and Much More

Here's a great article from a very helpful website that will give you all the tools and steps necessary to create a bootable rescue / live recovery disk that can extract the Windows product key and much more.

Three Methods to Recover Windows Product Key from Dead or Unbootable Windows

After recovering your product key, move back up to one of the previous repair routes and try to do a repair installation.

If that fails too, move on down to the final route!


There are several excellent system rescue and recovery suites with the ability to boot into a variety of repair programs that will certainly have a helpful tool to finally solve your problem. It might take a little more research and trial and failure before you succeed, but many people (myself included) have been able to rescue an unbootable system with one of these disks.

Here's a great list of the most popular and well tested recovery suites:

Best System Rescue Discs for Windows PCs

It may take longer than you hoped to fix the system, but rarely have I been faced with a problem like yours and not been able to eventually solve it with some dedication to troubleshooting, learning how to use recovery tools, and patience when you don't always get it right the first time - but now you'll have a handy recovery solution ready to go the next time you or a friend encounters a similar problem and it won't take nearly as long to fix!

Hope you're able to get everything working and learn something new through this process!

Original Answer (Changed due to additional contextual information from OP):

Have you actually attempted to plug the hard drive in to a new computer? Because I can't even count the number of times I've successfully used an old hard drive on a new system without formatting. You don't need to do all that VM/copy stuff. Just boot off your current working drive and then access the old drive like a secondary / slave data disk. Shouldn't have any trouble.

The only situation where this would possibly not work is if you're going from Windows to Mac or Linux, whereas with Win7 you're most likely utilizing a MBR-formatted disk and with the others you'll most likely be running with GPT formatting. In this case you may have trouble seeing the old data natively in the new system. However, with some partitioning software you may be able to change the format table structure without damaging any data.

  • I tried this but the OS just loops, It reaches the starting windows screen then restarts.
    – Mr.J
    Nov 8 '17 at 0:15
  • I went ahead an updated my answer with a lot more detail, hope it helps! Nov 8 '17 at 8:28
  • New comment, could I use this for Windows 7? its seems they are for windows XP systems.
    – Mr.J
    Nov 9 '17 at 2:05
  • @Mr.J The solutions I provided will work for everything from Windows XP to Vista, 7, 8, and even Windows 10. The Windows Recovery Environment (also known as Windows PE) looks visually similar to XP with a touch of 7, but can perform repairs even on Windows 10. I do advanced system maintenance and PC repair / recovery for a living, running my own local small business, and the tools I've outlined above are what I use on a frequent basis, depending on the situation and specific needs of the client. I carry a multi-boot USB drive with protective firmware and a hardware write-protect switch-- Nov 9 '17 at 3:21
  • --(to protect against malware and advanced persistent threats) which can boot into both Win 7 and 10 installation discs, several different Linux live distros, and a selection of system rescue discs; between all those, as I expired in a but more detail above, you can repair ~95% of computer malfunctions. There's always the more advanced cases with extensive damage or persistent malware that requires the use of OS or hardware virtualization and a trip to my shop to repair. But again, nearly every case where a client had me fix the exact same issue you've described I was able to quickly repair by Nov 9 '17 at 3:23

You could try Acronis Boot CD as Tetsujin suggested, but you can connect it to another PC, boot from the PC's OS, try to connect the HDD from the OptiPlex as a VM hard disk and try to delete the old drivers.

Then, connect it to the new motherboard, connect to the Internet and find the drivers for it.

  • the computer where the HDD came from, the Optiplex, is completely roasted, literally, and no joke. Surprisingly the HDD is good, bot internally and externally, so I cant use the Optiplex anymore.
    – Mr.J
    Nov 8 '17 at 1:33

These scenarios can be many and varied but I can say that if the chipset of the new motherboard (in a new or used replacement system) is the same make in the same generation, the following will often work:

  1. Practice using the F8 interrupt key to bring up the Recovery boot menu at Windows startup, to ensure you know what to do when it matters. Know your Windows Product Key before you start and have it available in case needing to enter it. Don't rely on Product Key labels from original towers or desktop units as they can't always be read and might not have been used for your original Windows installation. There are Windows key display utilities online to show them for a working system, appreciating that doing this might not be possible before starting.

  2. Fit the used bootable hard drive into the replacement system as master drive. If you don't know the basics of connecting PC hardware, read up on what to do first. Make sure the system has an interface for either IDE parallel or SAATA drives, whichever is needed. Some motherboards have been able to use either but most are SAATA today. If Master/Slave is an option, choose Master, rather than Slave.

  3. If possible and available, use the original video adapter card in the same type of expansion slot (eg. AGP or PCI Express), connecting the display screen to, it once fitted. Usually an onboard video chip will not mind an extra video adapter connected as well. If unavailable. try to discover the onboard video chip model, such as nVidia, Intel, ATI, etc. also the sound chip and UTP network adapter model, so as to manually download the drivers later. If the new system motherboard has a non-Intel integrated chipset different to the original (such as ViaTech or SiS) then this might not work.

  4. Connect all essential bootup hardware, without external USB devices, other than keyboard/mouse. Avoid any cordless mice or keyboards initially. Power on and be ready to use F8 at the right moment. From the Startup menu choose 'Safe Mode with Networking' then proceed. Allow Windows time to startup then try to get to the logon screen. If you get this far you're almost there. Login as a full Administrative user to see if the Desktop appears at low screen resolution. Remember to wait a few minutes for system hardware configuration.

  5. If the system hangs, or keeps restarting, repeat the same process up to twice more, then (if no joy) try Safe Mode only to see what happens. If you do get to the desktop and can see the start button, task bar etc. you now have the means to check hardware functionality, especially to connect via a network cable to a router or network socket. If you can get online then the rest should be relatively straight forward. If Safe Mode only works then previous devices can be removed from the Device list, prior to trying Safe Mode with Networking again. If this login works then view what hardware devices are installed and any that show in yellow as not configured. these can be installed manually as long as you know what they are (this not always obvious).

  6. If Safe Mode with Networking works then try a normal startup and keep fingers crossed. Again check functionality of video adapter, audio, network adapter etc. troubleshooting each manually as needed. If you don't get this far, another approach will be needed with no guarantee of success. A USB wireless adapter with known driver can be useful if hard wired UTP isn't yet working. Sometimes Windows needs to be reactivated, either by phone or Internet. Beware going online without adequate security software.

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