Questions about Dual Channel.

I'll be picking up an Abit NF7-S soon, should be a nice upgrade from my current board. Anyway, it supports dual channel memory, what I'm wondering is how much of a performance gain will I see from running 2x256mb VS 1x512mb?

Also, what if I were to get 2x256, then add a 512mb stick later on, would I loose my Dual Channel operation?

From what I have seen you will not gain a whole lor with dual channel on an AMD, it seems to prove better in the Intel world. For you second question as long as you have it set up right you will not lose the dual channel.

You won't lose the dual channel, though your overclockability might suffer.

Dual Channel on an AMD gives a slight performance boost. This is offset by the fact that a single DIMM usually overclocks better than two.

If you're not looking to upgrade your amount of RAM in the near future, dual channel would be a good way to go. If you're planning on buying a second stick pretty soon, then I'd go single.

Use the 512 stick in your channel 1/A slot and the 2 x 256 in your channel 2/B slot(s) and you will be running in dual-channel mode with all your ram. If you use a single 256 stick in channel 1, then the max memory that can be accessed by both controllers is, by design, limited to 2 x ram in channel 1, or 512. This would then result in only 256mb of ram in each channel being accessed by both controllers concurrently, with the remaining 512 of ram in channel 2 being accessed by the channel 2 controller only.

While technically still running in "dual" channel mode (and CPU-Z, for example, would display as running in dual channel), only half of your ram would be.

The best set up is to match your memory equally, and I believe, by placing your largest single (if not all of equal size) stick in your channel 1 slot.