Comment by e2le
15 hours ago
How do you know they weren't faulty? Blip flips are usually silent unless you have ECC memory or are actively testing for faulty cells.
Somewhat recently, Firefox implemented memory testing in their crash reporter and found 10% of reports were due to bit-flips[0].
If it weren't for reading that HN thread, I would never have being prompted to check and find the faulty memory in my laptop. It would have gone undetected and continued to corrupt whatever was stored in the affected cells. I did run memtest86 not long after I bought the laptop, so sometime between running that first memtest86 and the 12 months after, it developed the fault.
Non-ECC memory sometimes fails and there's a good chance you'll never know.
Keep in mind that a passing memtest86 does not prove the absence of faults that could present themselves under different usage patterns.