Do errors in Memtest86+ definitively mean something is wrong with my RAM?
It's fairly safe to say that there is a hardware fault when MemTest86 fails. RAM is the most likely culprit, but there are a few other things that it could be in rare circumstances. I'll list them in decreasing likelihood:
- RAM - Yes, the RAM could just be bad. This is the answer at least 95% of the time.
- Power Supply - RAM operation is fairly sensitive to power fluctuations. An ailing PS could have all sorts of odd effects. The only real test is to swap in an known good PS with lots of extra capacity.
- Motherboard - This connects all of these components together, leading to a lot of possible failure points. A motherboard problem is just as hard to diagnose as a power supply, though.
- CPU - You'd probably see other problems if your CPU was having trouble. That said, modern CPUs have memory controllers built in, so memory errors could be a result of a problem CPU. Running a CPU stress test is a fairly reliable way to ferret out these issues.
Memtest86 can also report errors if the memory timings in the BIOS are wrong. This can happen if you've modified the default timings, or if the SPD values embedded in the modules are incorrect, or if the BIOS is interpreting the SPD values wrong. I once had the latter occur. A BIOS update fixed the problem, so I suggest you try that before swapping out hardware.