This comes from a guide I posted at Notebook Review:
So you just got your shiny new RAM, and you can't wait to upgrade your computer. Congratulations! You've been through the decision making process, scraped up the cash, placed the order, eagerly followed the tracking number, and now it's finally in your hands! This is what you've been waiting for!
But before you install those new sticks, close everything up and ride off into the sunset, there's one thing you really, REALLY should do first...
TEST THAT RAM
The sad fact is that RAM can easily get damaged, for a variety of reasons: manufacturing, packing, shipping, or even installing. Most damage comes from static electricity, and the effects of such damage can result in a system that randomly reboots once in a while, or one that won't boot at all. The latter is pretty obvious, but the former is usually blamed on the OS or something else. (Bad RAM is frequently the true cause of problems with Windows)
In any case, you should ALWAYS test your new RAM thoroughly before considering yourself "done" with it. It's also very important to do this as soon as you get it, so you won't miss the return deadline date. A lot of RAM has a good warranty on it, so that's also an option if you missed the window; you'll just have to deal with the manufacturer directly (which isn't really that bad, at least when I dealt with OCZ).
The best package out there for testing is called memtest86+. The original project, memtest86 (note the missing "+" sign), is still around, but was not updated for a long time. So the memtest86+ guys took over.
Memtest86+ is very easy to use. All you need to do is:
Running the test will take some time, and it's directly dependent on how much RAM you have. One full pass of tests took 45 minutes on my system while testing 2GB of RAM. Don't worry about the time -- just start a test before you go eat dinner or something. My experience has been that bad RAM shows up pretty quickly, but it's worth it to run at least one full pass. I often let it run all evening if I'm off watching TV or something.
What am I looking at here?
Dealing with Errors
If you get errors, it will be pretty obvious. The part of the screen that's currently blue and empty will fill up with RED error messages, you can't miss them. What the errors are really doesn't matter. All you need to know is that it's bad. A good RAM module should have zero errors.
At this point, all you can do is return the module to where you bought it, or get a replacement under warranty. There's no way to fix it, and there's no reason to live with it either. Do not put up with a bad module, get it replaced. Replacing it is the only way to make sure manufacturers don't get used to the idea that their customers will put up with bad quality.
Typically, all you need to say is "I tested it with memtest86+, and it was bad." Any memory manufacturer will know exactly what you're talking about, and shouldn't give you a hard time. Some places will cross-ship you a new one, while others will wait for you to send back the broken one before they'll replace it. That's just the way it is.
How important is this?
Personally, I've had about a 40% failure rate with the RAM I've purchased. Maybe I'm unlucky, or just have a lot of static electricity around, but I've almost always had to return at least one of the modules I've received.
RAM is one of the really base components in your system, and if it's bad, you will not be able to have a stable system, period.
If you have other questions, you can take a look at the memtest86+ F.A.Q.