daviangel -> RE: How many passes for memtest86? (4/14/2009 9:35:23 PM)
3-4 passes is good for testing an overclock I agree. But if someone attempts to look for a bad stick of Ram using only 3-4 passes you could still easily have bad Ram getting past a 3-4 pass test.
I see a bunch of guys with freezing problems run a few passes with all sticks in and then conclude the Ram is good. Unfortunately, an incomplete testing procedure like that won't fix anything.
I remember when I ran Memtest boot CD for 25 passes which my old Ram passed but I still had freezing problems so the Ram didn't work right and had to be replaced. Although Memtest for Windows and Prime blend would freeze up which were my best clues.
When I say 20 passes I mean on a single stick using the memtest boot CD and looking for a bad stick of Ram not just testing an overclock. All the info I could find insisted that 20 passes was needed to conclude if a stick of Ram was bad or not.
Also, from what I read about this, it's very difficult to find a bad stick of Ram using the boot CD when you are testing more than one stick.
You're supposed to test them individually unless they were sold as a matched pair from my understanding and that's the way I usually do.
Q » I have two Corsair Memory modules that work fine together but when I added two more modules of the matching part number, they won’t work. A » We test these modules as they’re sold. In other words, a 2GB kit is tested only as a pair, not with two other modules. We’re not certain how two kits when put together will perform. While it is possible to get 2 separate kits working together, it will most likely require adjustments to be made in your BIOS to get the modules up and running. If possible, we suggest lowering your memory frequency and slightly increasing northbridge voltage. Please consult your motherboard manual for information on how to make these adjustments.
If you’re not comfortable making these adjustments, or if the BIOS doesn’t allow for these adjustments to be made, you might want to consider our 4GB memory kits.
Also, Corsair recommends 3 or 4 passes:
How do I use memtest? A » There’s a readme.txt file included in the package you download from memtest.org which will explain how to setup the program. We recommend using the default test on each module for three or four passes. This will take a while but it gives the modules the best opportunity to fail.
Why not stick with 3 or 4 then? Because it's completely arbitrary and up to how long you want to wait around testing memory.
Anyways, I stick by my original recommendation since that's what the official memtest FAQ also suggest and I don't have extra time to wasting running extra tests when 1 run will tell me most of the time.
"To conclude, one successful pass of memtest will give you a pretty good
idea that your memory is ok, only in rare cases will there be errors
showing after the first pass. To be sure though simply have the test run
overnight or even for a couple of days depending on the level of importance
of the system."
But like the FAQ says it's really up to you. Anyways, in the past all my Corsair memory I RMA's and Corsair quickly replaced failed memtest after the 1 run not 3 or 4. After testing the said ram in other machines of course to rule out other factors.
If your system is really that unstable you should be spending that extra time troubleshooting other factors.
- If memtest86+ shows no errors does that mean my memory is not defective?
Of course no answers are definitive, no matter how good memtest86+ is or
will become there is always the possibility that a particular type of error
will go unnoticed. As long as you are having no problems with the system it
will be pretty safe to say that the modules are good. If you are having
problems with the system however you will just have to check elimination of
factors, ie swapping the modules for new ones and/or testing with modules of
a different brand/type. See the question 'What is elimination of factors?'
for more information on this method.