It's the exact same process. Boot into modGRUBShell and change the last number of the offset. Change 2 back to what it was originally.
Why change it back ? If you change any of the EHCx and XHCI related offsets from the defaults you should change all of those together not just some of them.
For anyone that wants to revert all the changes, reflash the BIOS and they all go back to defaults.
Quoting the above post because I have a related question. Working on getting OC/Big Sur on my Dell Precision T1700 MT. After making the EHCx and XHCI BIOS changes, my machine loses all USB functionality. It will boot a SATA SSD but none of my USB ports work after making the changes. To regain USB, I have to remove the CMOS battery. Wondering if anyone might have some thoughts on this...
I understand this is not a T1700 support thread, but I think it would be great if we could add another related machine to the 'success' list.
My troubleshooting:
1. Extracted T1700 bios file attached below to verify setup_var names
2. Replace CMOS battery
3. Reflash BIOS using Windows, to latest which for T1700 is A28 (7/15/2019)
4. Make all recommended changes in the UEFI bios
5. Use modgrubshell and check all setup_var values. The interesting thing is that the CFG and DVMT values seemed to persist after the reflash. At this point, set the 5 recommended EHCx XHCI variables.
-- After rebooting from the grub shell, USB functionality is lost.
So, any ideas where I might be missing something or what to troubleshoot next? Should I try
not disabling EHCI1 and EHCI2? If I do not make any of these changes, will I just have intermittent USB issues?