k I am running a AMD64 with 512Mb (2x256)twin RAM

I want another 512MB or even 1Gb, now reading a few forums, I read that there is not much of an improvement with twin ram over non-twin ram

So basically my question is, can I put non-twin ram on the second channel on my mobo?

Cause its cheaper to buy 1 512Mb than 2x256Mb twin ram...and am on a budget :P

From your post, I couldn't tell whether you know this or not:

The dual channel ram you have now in your computer, are just like any other dimm's you can buy. By buying a twin kit, you get two identical dimms (usually with consecutive serial numbers) to assure they will work together as dual channel ram. So you can put a single dimm to the other channel, but I'm not sure if the ram you previously had will continue working as dual channel. But it will, of course, still work.

But like you said, it doesn't really make much of a difference.

Great thats all I need to know!!

So I'm current using 2x256Mb twin Ram (and yes its all to do with tolorence via manufacturing) basically if there is no real difference in speed between twin and non-twin ram then I am quite happy to but 1 stick of 512Mb ram to use on the other channel.