It's less of an issue now, but there were stability issues in the early days of DDR5. Memory instability can lead to a number of issues including being unable to boot the PC (failing to post), the PC crashing suddenly during use, applications crashing or behaving strangely, etc. Usually it's a sign of memory going bad, but for DDR5 since it's still relatively young it can also be a sign that the memory is just too fast.

Always check and verify that the RAM manufacturer has validated their RAM against your CPU.