To be fair, memtest86 is a really weak RAM stability test, but I don't think it's your ram stability either way.MEMTest86 just passed. Regular run, 4 times. All looks good here as well.
My experience is that Mobo chipset updates are way more important, and can cause kernel panic if not kept current.So the BIOS was really ancient - Version 1.0 - with around 17. or so releases after that. So I updated that and will run the HDR playlist again, overnight..