Memtest86+ 8.10 tests RAM before Windows starts. It cannot run inside MBDR Rescue.

ON AN MBDR RESCUE USB
Finish recovery work first. Restart into the PC's firmware boot menu. If it offers Boot from file, select this USB and \EFI\MBDR\memtest64.efi. The usual USB boot entry still starts MBDR Rescue; there is no combined boot menu.

OTHER PCs / LEGACY BIOS
Use the included Memtest86plus-8.10-x64.iso with an ISO-capable boot manager, or write it in raw/DD mode to a DIFFERENT blank USB using a suitable image writer. Writing the ISO replaces that USB's contents, including any MBDR installation. Copying the ISO file to an ordinary USB is not enough.

STANDALONE UEFI FILES
Save Memtest boot files creates a folder containing EFI\BOOT\BOOTX64.EFI. Copy the contents of that new folder to a separate empty FAT32 USB, then select its UEFI USB entry at startup. Do not copy over an existing recovery USB's EFI folder.

SECURE BOOT
Memtest86+ is unsigned and requires Secure Boot to be off. MBDR does not change firmware settings. If you choose to change Secure Boot, have your BitLocker/device-encryption recovery key available first; the change may trigger recovery. Restore the original firmware settings before normal Windows use. If settings cannot be changed, this memory tester will not boot. This does not affect the normal signed MBDR recovery boot path.

TESTING
Tests start automatically after boot. Let at least one full pass complete; repeated passes give more coverage but no finite test guarantees fault-free RAM. Errors can involve RAM, CPU/memory controller or unstable settings. F1 opens options; Esc exits and reboots. Photograph results before rebooting: this integration does not save a report automatically.

x64 PCs only. Memtest86+ is the free GPLv2 project, distinct from PassMark MemTest86. Unmodified upstream binary, source and licence are included.
https://memtest.org/
https://memtest.org/readme
