This is on a non-EFI system. Memtest use to work on my systems before (Have 5 Fedora 34 machine and the standard memtest started giving the blue screen when selecting memtest). The memtest worked fine with syslinux boot from flash, and use to work with grub4dos boot, but now that requires a memdisk setup to load it. Just was trying something similar with grub2.

With grub4dos use this in menu.lst
title memtest
find --set-root /MEMTEST.IMG
#Uses memdisk from syslinux 6.04pre1
kernel /memdisk
initrd /MEMTEST.IMG

in /boot/grub2/grub.cfg use
menuentry 'Memtest' {
              insmod part_msdos
              insmod ext2
              set root='hd0,msdos5'
              if [ x$feature_platform_search_hint = xy ]; then
                search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 --hint='hd0,msdos5'  fa908208-22bd-4031-b620-841498e0708c
              else
                search --no-floppy --fs-uuid --set=root fa908208-22bd-4031-b620-841498e0708c
              fi
              echo 'Loading memdisk'
              linux16 /memdisk iso
              echo 'Loading iso'
              initrd16 /memtest86+-5.31b.iso
}

Have tried a little with EFI, but haven't found a way since it doesn't like memdisk??

On 8 Jan 2022 at 10:43, Tom Horsley wrote:

Date sent:      Sat, 8 Jan 2022 10:43:40 -0500
From:             Tom Horsley <horsley1953@gmail.com>
To:                  users@lists.fedoraproject.org
Subject:          Re: Fedora's memtest option doesn't work, but found something that
                      seems to??
Send reply to:           Community support for Fedora users <users@lists.fedoraproject.org>

> On Sat, 08 Jan 2022 16:48:26 +1000
> Michael D. Setzer II via users wrote:
>
> > I've noticed for a while running memtest from grub2
> > menu just gives a blue screen and locks machine.
>
> Memtest and EFI seems to be tricky. I had to download the EFI compliant
> memtest86 (NOT memtest86+) and make a bootable usb stick to run
> memtest on a new EFI only system I got.
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