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I have 16GB RAM as four separate 4GB cards. I ran memtest86+ on my PC and got about 3000 errors. Then I removed three rams and ran the test on one ram at one time. None of the rams separately showed any faults or errors.

So after that putting all the RAM cards back in and running memtest86+ gave zero errors or faults. After another day I just ran the tests again and on the first run it gave about 400 faults, and the second run gave only about 30 errors.

I'm confused by these results I can't really call on the warranty since the errors come and go and cannot be replicated successfully!

Any ideas on what may be causing this?

My RAMs are 4GB DDR3-1333 cards of a brand called ADATA.

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migrated from serverfault.com May 3 '12 at 11:46

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memtest86 is sho shiet! it was used back in the day years ago. I had many memtest show 100% OK but the ram was D.E.D - because todays ram uses clever ECC correction, fault redirection and all that.. But still will crash a PC now and then. Want to test a ram stick, put a new one in. Most RAM has limited lifetime warranty.. why shmuck around with test tools.. if you went for 'el-cheapos' then suffer! If you got expensive RAM then most likely your BIOS timing is out or under Voltage or something daft. –  ppumkin May 3 '12 at 16:26
    
They weren't 'el-cheapos' :-P Pretty much the same amount as most other RAM brands out there.. Yes but to get the warranty I should show whats wrong first right? –  Thihara May 3 '12 at 16:44
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Not with ram. You just have to say your PC is crashing and you put in other ram and it works (this should be true though ;) ) If 1 year has passed you have to contact the manufacture direct. If less than that and in EU you are entitled to the seller handling it for yu. –  ppumkin May 4 '12 at 13:46
    
Not in EU, In Asia!! But thanks for the tip!! Well lets assume it will fix itself with new RAM ;) –  Thihara May 4 '12 at 13:52
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4 Answers 4

The errors probably don't show up until the RAM gets warm. Either run the test longer or blast it with a hair dryer while testing it. (Be careful you don't overheat anything else.)

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Every time I ran the test for over 9 hours... Is that not enough or should I run it longer?? –  Thihara May 3 '12 at 1:34
    
Time on a memory test just increases the loops it performs with possibly alternate test patterns - it doesn't necessarily mean it's better or worse. A memory test should properly test every bit with patterns that will ensure it catches a malfunctioning bit. This usually means at least 3 patterns/runs per bit. –  Eli Sand May 5 '12 at 3:43
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Any combination of factors can cause memtest errors.

  • try testing the rams in different slots
  • try running the tests for a longer time, for the boards to heat up (same for cpu + chipsets on the board, any of these might be causing errors)
  • try different combinations of 2, 3 4 rams in different slots

But still, if any combination, after any time, produces errors, it should be a cause for replacement... better replace now, then have a massive breakdown in near/far future, with data loss,.. or worse.

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You've tested the memory itself, but you failed to realize that in order to test the memory in a computer, you're also testing the rest of the motherboard and the memory slot(s) used. If the memory doesn't fail at all in one slot, try others (if you can). It could be a fault of the motherboard.

To truly test memory, you're supposed to use a memory module tester which is a stand-alone single module tester. That way you minimize the external factors for possible "faults" being reported.

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The thing is after testing individual RAMs in one slot, I put everything in again and tried, it didn't give any errors then. So I ignored slot testing. But I will try the individual slot testing in the weekend and post the results. Any idea of a good memory module tester? –  Thihara May 3 '12 at 1:38
    
@Thihara - This proves that it could be the motherboard that is starting to fail. Because you certainly did not test each and every slot with each and every memory. I know this for a fact. –  Ramhound May 3 '12 at 13:05
    
Yeah probably something in the slots or motherboard.. Will test thoroughly on weekend.. –  Thihara May 3 '12 at 16:45
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on some (PC-based) video-servers we had some issues with ram-modules when they were hit (gently) with the isolated part of an screwdriver. After shutting down the machine, removing the modules and cleaning the contacts with a fat-remover and special cleaning fluid the problems were gone.

The one who has installed the ram-modules has probably touched the contacts with his fingers and therefore created a corrodating layer.

clean contacts -> no errors any more

Of course the machines were unstable before, not only when we were knocking...

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I'm biased towards this possibility so I will clean after running the tests and we'll see. Any recommendation for a fat remover and cleaning fluid? –  Thihara May 3 '12 at 1:40
    
We use sometimes "LR" from Kontakt Chemie. This a cleaning fluid/spray to clean up PCBs. Or: "Kontakt-Spray" from Kontakt Chemie. You have to take care that there is no residue on your contacts (like with oil or "polish effect") –  ppuschmann May 3 '12 at 15:58
    
Do not use rubbing alcohol! –  Eli Sand May 3 '12 at 23:48
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