Mixing RAM

Hey guys, first post!

Anyway, my current RAM config is 2x512 DDR400 in dual channel, so I still have two more RAM slots available. I was thinking about upgrading to 2GB. I was wondering if I could stick a 1GB stick into one of the remaining RAM slots, or will I have to buy two extra 512's and use those?

Also, my RAM manufacturer doesn't sell the RAM in my country any more, so I will have to mix RAM brands. Is this ok?

Oh and one last thing. In BIOS, my computer tells me my RAM is DDR333. I have seen people say this is an error, but will this affect me if I get DDR400 RAM? Is there a way to check for definite what type of RAM I have? If it really is DDR333, will I have to buy DDR333 RAM?

Thanks for any help!

It's fine to mix brands. Depending on the chipset used on the motherboard, handling large amounts of RAM or more than 4 banks (a bank being each side of the RAM stick with RAM chips on it, up to 2, and commonly seen on 256MB modules and up) may not be able to run the RAM at top speed. Other cases, it may go with the lowest common denominator to be on the safe side, and you can manually adjust this without ill effects. It does depend on your motherboard, however.

Well, here is my mobo
ASRock Motherboard - Product - 939S56-M - Overview

Sorry I would have no idea how to find out that information. But if it was designed to hold four RAM's, surely it would be able to run them at top speed? Even so, if it was not running as fast, I can take a small speed drop. As long as its nothing drastic. Thanks for the help!

Not necessarily. The Athlon64 family has the memory controller on the CPU die itself, rather than coupled with the motherboard chipset. The more banks in use, the harder it is to keep them running at the fastest speed and timings. The good news is that the memory speed has very little effect on the Athlon64 design, in part due to the memory controller and that the CPU's performance lies mostly with the CPU clock speed.

So you would recommend getting a 1GB stick as opposed to 2X512's?

If you're going to run 2GB, yes. One thing to consider is that dual-channel memory functionality requires equal pairs of RAM, and the A64 doesn't tend to have this work very well with odd numbers of sticks.

Oh, well what do you mean doesn't work well? If it didnt, then surely it would be better to get 2x512's?

It has to do with the memory controller on the Athlon64 itself, and AMD has it setup a certain way. It likes equality in memory pairing, and isn't as flexible as some newer chipsets from Intel that use the traditional memory controller location in the chipset. AMD will probably get more flexible with memory configurations over time, but right now, the way it's designed just works better when using equal sticks and sizes of RAM in dual-channel.

Feel free to try it, but just know it can be a bit problematic for people. I'm not saying it never works, just that this is a known issue.