Why does my desktop stop booting up with an external 1TB USB drive attached
and switched on? It boots normally from the normal internal 80GB drive with the
external 1TB drive switched off!!
This happens surprisingly often – I’ve heard many people mention it.
Typically, they’ll just leave the external drive powered off until the
machine has finished booting; at which point, they turn it on and Windows
Depending on how you use your machine, that might be the most appropriate
On the other hand, it’s also possible that it’s a very simple fix.
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Change the boot order
The solution is to change the boot order in your computer’s BIOS so
that it looks at the hard disk before USB devices or doesn’t look at USB
devices at all.
Unfortunately, I can’t tell you exactly how to do this – the BIOS controls your
computer before Windows starts and is unique to your machine (though often
common across product lines or even manufacturers).
You’ll need to check your system documentation to determine the exact steps.
In general, when your computer boots, there’s a key that you need to press right away
that causes the BIOS to enter its configuration mode instead of booting
Windows. Then, somewhere in there should be an item called “boot order” or
something similar. In that, you’ll want to make sure that your hard disk is checked
before the USB devices if you want to boot normally while that external drive is
connected and plugged in.
What’s boot order?
Your computer’s BIOS is programmed to look for a device from which to boot.
It typically works something like this:
- Is there a floppy disk inserted? Try to boot from that. (Even if your
computer has no floppy disk, it’s very likely that your BIOS still includes this
- Does the hard disk have a recognizable boot sector? Try to boot from
- Is there a CD or DVD inserted and does it have a recognizable boot sector?
Try to boot from that.
- Is there a USB device inserted and does it have a recognizable boot sector?
Try to boot from that.
- If none of the above apply, give some kind of “no bootable device found”
The boot order in the example above is: floppy, hard disk, CD, USB. As
mentioned above, you can typically alter the order in which the BIOS checks for
devices from which to boot.
Things get a little interesting because of this phrase, “Does it have a
recognizable boot sector?” As I understand it, there’s really no standard way
to answer that question. In your case, not only is the USB drive earlier in the
sequence than your hard drive, but if the BIOS is checking for a boot sector on
that device, it seems to think that it’s found one, even though there’s nothing on
that USB drive to boot from.
If you occasionally do boot from USB
Here’s where things get sticky.
If you actually do have other USB devices from which you occasionally want
to boot your machine, you probably do want to have the BIOS check USB
And not just before your hard disk, but before that other USB device, your
external hard drive.
I don’t know of a way to control the order that BIOS checks the USB devices
if there’s more then one.
So you’re left with the workaround that you’re using now:
- Let the BIOS check for bootable USB devices before it checks the hard
- Turn off your external hard disk when you boot (be sure to click Safely
Remove Hardware if you’re rebooting and Windows is still running), and turn it
on again after Windows is running.
It’s messy, but it works.