Run MemTest86 for at least 4 passes to catch cold solder joints.

Yes, MemTest86 is the right tool. A bad solder joint usually shows up as errors that repeat at the same memory address or display a pattern like a “stuck bit” (e.g., every byte has bit 3 stuck high).

You want to boot from a USB stick with MemTest86 (free version is fine) and let it run for multiple passes. A single pass might miss intermittent failures. Cold solder joints are often temperature-sensitive — they work when the board is cool, then fail as it warms up. So run it for several hours.

Look for errors that consistently appear at the same address across different passes. That’s the smoking gun for a bad connection. Random errors that move around each pass could be a voltage problem, bad RAM module, or overheating — not necessarily your solder work.

If you see errors, first reseat the board (if removable) or check your solder joints under magnification. Reflow any that look dull or have gaps. Then test again.

A clean MemTest86 run