I've recently built my first PC and got it all working (yay!) except for the USB 3.0 ports. I don't think any of the USB 3.0 ones are working, there are some in the MB/back and also a couple at the front, I did plug in the USB 3.0 wire from the case to the mb, and made sure the USB 3.0 option is enabled in BIOS. I can't update the mb drivers as there are only options for windows on the msi site. MB is MSI 970 Gaming.

If I go into BIOS, I can see the devices I have plugged into the USB 3.0's, but if I try to see them through the command line once booted, they aren't there.

I had the same problem. Resolved it by adding in /etc/default/grub:


Then sudo update-grub, reboot and voilà!

Just to clarify, I'd like to get to the point of plugging in a USB device (mainly into the front ports) and have them recognized. I'm not too concerned about whether they function as USB version 2 or 3 right now, so long as they work.


1 Answer 1


Use whatever text editor to edit the following file as root:


The editor will open showing you the contents of grub configuration file. Search for this line:


Change the line by adding iommu=soft and now the line will look like this:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash iommu=soft"

Save the file and exit text editor.

Now, type to the terminal:

sudo update-grub

Finally, reboot your PC and the recommended change takes effect. Hopefully all your USB 3 ports are working now.

Besides the recommendation you were seeking help on I would look in your BIOS and carefully examine all USB related options.

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