System does not boot when the USB flash drive is connected.

When the SanDisk USB key is connected to the server, the server does not boot.

I have the same problem with 8GB Cruzer Edge and a 16GB Extreme USB 3.0 and it does not make a difference if I connect them on a USB 3.0 or a USB 2.0 slot.

All USB ports are enable on the BIOS.

Altering the boot order does not help.

Is there any special settings I need to chose to allow normal operation on the server with the USB key connected ?

Are SanDisk USB storage products compatible with main stream servers?


I take it the server boots when the USB drives are not connected?  If the BIOS has the hdd set as the primary boot device and that isn’t happening there is a BIOS problem.  Check the machine’s vendor and see if there is an update. 

The server boots without problem without the SanDisk USB on it.  It boots to the OS without any USB falsh drives or with USB falsh drives from other vendors. 

How does these USB SanDisks identify themselves to the BIOS to create this problem?

Are these flash drives new per chance?  Some new devices are config’ed as Fixed rather than Removable and that could be confusing the BIOS.

Are these flash drive old per chance? Some older devices had in addition to the data partition a partition config’ed as a CD drive and that could be confusing the BIOS.  With those I’ve found ignoring the booting error and pressing Enter works.

Do you see any error msgs when booting with the flash drives in the machine?.

These are 1+ year old drives, the Cruzer Edge is the older one but, none of them is older than 2 years.

There is no error message, just a black screen with a blink dash on the top left corner; at that point, there is no response except for Ctrl+Atl+Del

Even if there were an option on screen to hit a key to continue, it will completely kill the option of unattended reboot.  Competitive disadvantage.

How do I ‘fix’ these keys so they report are ‘removable’ as they are?  These are not CDs or Fixed drives, they should not be configured as such.


How do I ‘fix’ these keys so they report are ‘removable’ as they are?  These are not CDs or Fixed drives, they should not be configured as such.

Unfortunately there is no ‘fix’.  The devices were designed to support Microsoft’s Windows 8’s Windows to Go functionality, when it was thought to be the new USB drive standard.  Your best option is to sell the drives to people looking for hacks to convert their Removable drive to Fixed so they can partition them on Windows systems. :wink: 

If it helps, newer SanDisk devices are Removable again. 

Or you could make them booable, and config their boot menu to boot the hard drive as a default option.  Check out RMPrepUSB and it’s tutorial page:   

Lastly you can try returning them to SanDisk.  It’s a free function so it can’t hurt.

I would make sure that the USb drives don’t contain an active parition or boot code. The best way is to ‘clean’ them using the Clean button in RMPrepUSB. Then try them in the server again (unformatted).

If you still get problems then look for a BIOS update for the server and complain the the manufacturer if that doesn’t fix it.

I have seen some systems where this happens due to the order of USB device enumeration by the BIOS - so try swapping around and/or removing USB devices to different USB ports (e.g. remove all uneeded USB devices like mouse, scanner, printer, etc.).

If the server boots with a ‘clean’ USB drive - try formatting it with RMPrepUSB but tick the ‘Set partition as non-bootable’ check box first.



BIOS controls this behavior. Depending on which motherboard that you’re using, you might want to check the settings. Careful with the changes that you will make by the way. 

Changing the boot order or removing the SanDisk flash drive did not resolve the problem, when I disable Legacy USB support on the BIOS the problem goes away and the USB device seems fully functional from the OS.  I think I will need to reenable USB Legacy support if I want to boot from a USB device.

Is there a way to identify how the USB devices are configured?  On a previous post the SanDisk Guru indicated SanDisk USB flash drives can be configured and CDs or Fixed drives and that cannot be corrected.  How can I find out the configuration of these USB devices?  I think that could be the problem, if the USB is configured like something the BIOS does not understand, it hangs.


Is there a way to identify how the USB devices are configured?

It’s not that hard.  Open WIndows Explorer, plug the USB device in. If it shows as two devices then one is a CD and one is a Removable device.  If it shows only one device and it shows it as being Removable then that’s what it is and it’s not configured as being Fixed.  :wink:

On Windows disk manager both keys show as “Removable”, as other keys that do not present the problem at boot. What I noticed on disk properties, on the “Volumes” tag is that these two SanDisk Flash drives have 1 MB of Unallocated space. Other keys (a much older SanDisk, a Lenovo, a Lexar) do not report unallocated space. What is this for? Can that be the cause of the issue? On the BIOS, the SanDisk keys report as “USB KEY” while other keys appear as “USB FDD”. How can I find out a key will identify themselves to the BIOS from the OS? Do you have a utility to change that on the SanDisk Flash drives? Thanks

It sounds like the flash drives have been formatted.   As manufactured they are configured as large floppy drives, and they can not be formatted that way on Windows.  Windows formating will align the clusters differently and can indeed result in wasted space.