Boot from USB

Question

Hi guys,

I was studiously following this to enable undervolting on my Dell xps 9700.
I know this probably a touchy subject on this forum so please just take as context for the usb boot requirement.

https://www.ozbargain.com.au/node/559551
I am stuck at the last hurdle I can't get it to boot into the USB.
It's a usb stick with type c and it's been converted to GUID and formatted etc.

I have obviously turned of secure boot in the BIOS and allowed booting from thunderbolt.

In the BIOS there are fields to add boot options but you cant navigate to the usb drive. It just has these weird 4 options for recovery etc.

I have tried disabling other boot options and setting a boot option for EFI\BOOT\bootx64.efi but this just boots into windows.

Any ideas?

Jim Me · Accepted Answer

SUCCESS !!!!Ok so I did the obvious thing and dld a small linux iso and followed the instructions for formatting the disk, using a 3rd party app I formatted it in FAT32. Turns out my assumption that FAT and exFAT were the same was wrong, but this was in some way led by windows 10s formatting options. In my case it the USB was formatted to MBR FAT32 and it worked fine. Undervolting unlocked !!!Thanks for your input guys. Wish me luck

ejn63 · Answer

It is not necessary to alter the boot order. If the drive is bootable, press F12 a few times at powerup and a boot manager will appear. Select the drive from the boot menu and the system will boot from it.

If you do not see the flash drive in the boot menu, it's not being recognized as a bootable device.

XPS_Man · Answer

First of all do let us know if this works for XPS 9700 Appreciating your efforts  The steps do not require you to change the Boot Device in BIOS, you should be able to boot to F12 menu and choose the Boot Device listed under UEFI boot. If the Device is not showing as Boot Device in F12 menu it is either not formatted correctly or boot files are missing from it.    Step 2 (a,b,c and d) are very important once, Flash drive has be formatted in FAT32 and Boot files should be extracted in a folder name  EFI   Please also disable secure-boot as it can prevent machine to boot from unauthorized media.

Jim Me · Answer

Thanks for the reply. Firstly I tried f12 boot menu but it wasn't showing up, thus the post.

It clearly isn't being recognised for some reason.

"Format a spare USB drive to FAT32 on a GUID partition map."

I converted it to GUID and formatted in exFAT32 as that was the available option. And very carefully labeled the folders and contents.
I will give it another go !

Jim Me · Answer

For your info, I am undervolting by -105.5mv and all is stable with a small performance increase and a small temperature decrease.

A key point which some guides miss out is that the CPU core and CPU cache have to have matching settings. If you have different voltages on core and cache you will lose around 40% performance. But with matching undervolt I am observing a 2% or 3% bench improvement and a general reduction on the cpu of around 4c or 5c. No dramatic difference but it's free !!

nigelhorne · Answer

@ejn63​ The only options Dell presents are hard disk and PXE boot (IPv4 or IPv6).  Botting from USB is not an option in either the BIOS/UEFI or with Windows Boot Manager.

ejn63 · Answer

That either means the USB boot has been locked out by an administrator (is there an administrator password on the system?) or that the system does not recognize the flash drive as UEFI-bootable (what OS is on it and how was it prepared?).

XPS

Boot from USB

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