Recently my laptop's hard drive died (after 7 years of loyal service), so a replacement is due.

I was wondering however, if it is possible to connect a new external hard drive (SSD or HDD) via a SATA - USB (3.0) adapter to another laptop (currently I'm using a Mac), install an OS (Windows 7 or 10) on this hard drive and then unplug it, put it in my old(er) laptop, boot up and be ready to go or is this something that has to be done on the laptop itself? If this is possible, how would one go about doing properly?

I've been looking around the marvellous interwebs, found all sorts of methods for booting from USB, but that's not exactly what I'm looking for.


Possible, yes. Simple, no.

It would be far easier to just install the drive directly to the Windows machine, then use the Mac to create a USB boot drive that can then install the OS to the PC.

There is a guide here [there are many guides for this, because it's actually very simple.]

Use the Mac as a facilitator, not as an intermediate OS host.
Getting Windows onto an external Mac drive is not all that easy & even if you manage it, it won't boot the PC unless you first strip out all the hardware specific stuff.


This can only be guaranteed to work if the hardware in both devices is more or less identical. Otherwise its a case-by-case situation.

Windows installs drivers into the kernel both at install, and when the system has decided that a hardware change has occurred. That means that if you are to change the hardware present in a system between boots, the system will attempt to compensate, either by changing specific drivers, or by selecting a generic version of the driver with minimum functionality, until you install a more full featured one.

That does give some credence to your idea, but it is unknown until you plug it in whether the drivers at play will even boot the system under the new hardware. In the best case, it will reboot a few times, while installing the correct drivers. In the worst case, it will fail to boot completely.


The first thing you have to do is have a look in your BIOS to see if it does indeed support booting from an external hard drive. A computer that is 7 years old could or maybe not support this depending on the BIOS features.

Once you've confirmed that it can support it you have to enable the boot from that drive in the BIOS. Once this is done, you can go ahead and install whatever OS you want from any of those tutorials you saw on different websites, just adapt it so that you install the the external hdd instead of the USB key, they are essentially the same thing in this case.

  • This really misses the point. The OS creation is not going to be done on the machine it's intended for. By the time it gets to that machine it will be an internal drive. That's without mentioning that Macs don't have, & have never had, a BIOS. – Tetsujin Nov 21 '16 at 17:32
  • Nothing says that the old laptop is a Mac, only the newer one, so that would have to be confirmed. If the old laptop is indeed a Mac, then this is in fact not possible. – IronWilliamCash Nov 21 '16 at 17:34
  • I never thought for a minute that the old machine was a Mac, but the working one is; & by the time you've figured out how to get a Boot Camp Windows install working on an external drive on a Mac [not at all easy] then stripped out the hardware specific stuff that will prevent it booting the PC [also not easy] it would just be simpler to not do it that way at all ;) – Tetsujin Nov 21 '16 at 17:38
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    The old laptop is an Asus, so not a Mac (to clear any confusion). – Nico V Nov 22 '16 at 9:08

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