I'm considering buying two used 16GB DDR4 memory sticks from someone locally. The seller says they came from an Acer Nitro V laptop and has offered to install them in another laptop so I can see them working before I buy. The trip is fairly long, though, and running MemTest86 for around three hours would be inconvenient. Since I've used OCCT's memory test for checking instability before, would a roughly two-hour OCCT test be sufficient for screening both sticks, or is MemTest86 important enough that I should make the seller run it instead?
3 Answers
MemTest86 is still the more traditional choice for checking RAM, while OCCT is also commonly used for general system stability, CPU, and GPU testing. If the full MemTest86 run is impractical, a clean OCCT memory test is useful as a quick pre-purchase screen, but it cannot guarantee the modules will never show an error under different conditions.
OCCT and MemTest86 overlap, but they aren't exactly the same. OCCT is mainly a stress and stability test, while MemTest86 is more focused on diagnosing memory problems. For the most confidence, you could use both, although longer tools such as Y-Cruncher or TestMem5 can take several hours as well.
OCCT's newer memory test is a reasonable practical check, especially if the seller is willing to run it and show you the results. Just remember that a single error is enough to treat the RAM as faulty. A seller could potentially rerun a test until it happens to pass, so don't assume repeated clean runs cancel out one failure.

That last point is really useful. I hadn't considered that one failure should be enough to reject the sticks.