Is RAM 'error free'?

[eturnal]

I've run MemTest86+ several times over the last week, each with a different hardware configuration where I change out PSUs and Video Cards (or only use the on-board video card). In each test I'd get some errors. The lowest number of errors was ~20, and the highest was ~200. A 12-hour run of MemTest will get several passes... about 7 or so, and based on the errors on screen not all passes will generate errors.

1) Are these consistent and symptomatic of failing memory sticks or should there be something else to look at?
2) If the same test is being run on the same sticks, why would some passes return errors and others not?
3) With 8GB of memory being tested, will a couple errors (like a few bits being shifted) cause BSOD, Critical Errors in the log (reason, possibly from 'memory corruption', and poor gaming performance... or will all RAM return a few errors if you run tests on it for a long enough time?

Thanks for your time.

 

[mathew7]

1. PSU could cause sporadic errors if AC noise filtering is not good
2. same as 1
3. most surely yes. Depending on when the error appears. It could be a cell is altered but overwritten with no reading. But it's too risky. Servers have additional ECC bits to detect and maybe recover from altered bits.

Just to tell you my experience: my dad's (work) PC was rebooting for 6 months, at first after hours of working, until it could not use it even for 10 minutes (he also had a laptop, so it was low priority). Memtest showed lots of errors. After replacing the PSU with a spare I had (Thermaltake) at home, after 2 hours or running memtest reported no errors. So I told him to replace the PSU.

Another experience: I had a system which when I got home from work (so around 16 hours turned off), I turned it on and during the 1st windows loading it would crash, but after that reboot I had no problems. So after many memtest sessions with no errors I finally remembered to start memtest right after getting home. And there it was....1 bit on a cold system. Changing the slots solved this.

 

[eturnal]

Update: I pulled all the sticks of DDR3 out of my machine and ran the memory test against each individually. Each test was over 12 hours long and it showed that one stick was failing but the other three were fine. I've since ordered 8GB of RAM and I've been running the machine with 6GB installed. Unfortunately, the faulty RAM stick isn't why my computer was making a strange noise and removing the stick didn't fix my gaming issues. D:

Thanks for the help.