Since my 2017 iMac running Monterey has caught the kernel panic disease I'd like to check the RAM. It was suggested elsewhere that I try MemTest86. I followed the installation and boot instructions here: Creating A MemTest86 Bootable Drive..., but I can't get the USB drive to boot. I tried three different USB drives: a spinning drive and two thumb drives. dd seems to write to the drive just fine, with no error messages, but when I boot holding down the Option key, only two bootable drives are displayed: the internal SSD and an external bootable USB clone. The MemTest86 USB drive never shows up.
What have I done wrong?
What have I done wrong?