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Q: Can I mix different speeds & brands of DDR?

In a word, Yes.

But it doesn't always work and so, it is generally preferable to avoid doing this. The risks of running into problems are greatly increased if the modules used have different arrangement, size and SPD programming. A system will only run at speed of the slowest module, if you mix different speed modules. As you will see, some systems automatically detect the properties of memory modules being used, and set the system timing accordingly. They usually only look at the speed of the memory in the first bank when setting this timing. So if you use two or more dissimilar modules, it is advisable to place to the slowest module in the first slot. If the system doesn't't have this 'auto-detection' or you've disabled the 'auto-detection', it won't be much of an issue, but it's still good practice.

As well, if the goal is overclocking, often the best results are obtained with perfectly matched modules. Additionally dual channel architectures generally work very poorly with mis-matched modules. There is no guarantee a mismatch won't work for one reason or another, and it won't really hurt anything to try (assuming your data is backed up), but to maximize the chances of success modules should match.

Q: Which slots to use?

If you're using a single module, it's best practice to use the first slot. Q: I've had my single module installed in slot 2 for the last few months now, should I change it? No, it's also best practice to keep on using the slot(s) you're been using before. If you replace RAM, then insert the new modules, in the same slots the older ones were in before.

You may find the system overclocks better with the ram in a different slot. It is very hard to predict when this effect occurs, as well as which one might work best. In the overclocking game he who tries the most things wins, and if you are running an overclocked configuration that is asking a lot of the ram it is a good idea to try all available slots to make sure the one you are using yields the best results.

If using two or more modules in a non-dual channel motherboard, populate the first slot and use any other slots you wish.

If you're using two or more modules of unequal size, you will get the best performance if you put the largest module(s) (in megabytes) in the lowest-numbered slot(s). For example, if your system currently has 256MB of memory and you want to add 512MB, it would be best to put the 512MB module into slot 0 and the 256MB module into slot 1.


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by Exit See Profile edited by FastEddie See Profile
last modified: 2005-07-22 09:42:49