How should I run MemTest86 to check for memory errors?

Download the free version of MemTest86, write it to a USB stick, boot from it, and let it run at least four passes or overnight. One pass isn’t enough because memory errors can take hours to show up. The free version is fine — just use version 5.x or higher for DDR4/DDR5 support. If it passes clean, your RAM is stable; if crashes persist, the issue is likely elsewhere.