Run MemTest86 overnight.

Yes, MemTest86 is the standard tool for this. Download the free version, write it to a USB stick, boot from it, and let it run.

One pass isn’t enough — memory errors can take hours to show up. Let it run at least four passes or overnight. If it finishes clean, your RAM is almost certainly stable.

You don’t need to buy the paid version. The free one does the job fine. Just make sure you’re using the latest version (5.x or higher) because older versions don’t test DDR4/DDR5 well.

If MemTest86 passes and you still get crashes, it’s probably not the RAM. Could be your motherboard, CPU memory controller, or even a power supply issue.

Overnight is the price of certainty.