Hello there everyone.
I am very curious about some aspects regarding RAM configurations.

Q1: if i have 2 modules of 1GB each, activated in dual channel, and I add the third module of 1GB, same producer, frequency, latency, will it affect the dual channel configuration of the first two ?

Q2: To the best of my knowledge dual channel can make a difference of 8 to 10%. If so, wouldn't 3GB (identical modules) in single channel be more effective than 2GB dual channel ?

Thank you!

You need even number of sticks for dual channel. 2x1gb + 2x512mb would be 3gb in dual channel. Having 2x1gb and 1x1gb would bump it down to single channel.

Just get another stick. How much is 1gb worth of ddr2 800mhz worth those days? Like $15?

If you're using an Intel-chipset-based MB (or some non-Intel-chipset MBs), the memory controller will automatically run as much of the RAM in dual-channel mode as possible (Intel calls this something like "flex-mode" ). That is, it would run the 2x1GB modules in dual-channel mode, and the last 1GB single module in single-channel mode.
Q2 - The number of modules per channel doesn't affect the throughput. Think of it as a freeway: two lanes (channels) handle more traffic than just a single lane (channel).

Thank you guys for answering on so short notice. The information you provided is very useful to me. Mandoman, you made a quite interesting observation for me, and I am going to do some research over the internet to find out more about the "flex-mode" you mentioned.
dagger, interesting observation on 2x1gb+2x512mb, thanks a lot.
I am sorry if you got me wrong, I was only interested by the functionality of the given configuration, and not by making an investment in RAM. Therefore, the quantities presented were exemplificative, and yes, i know how much is 1gb of ram worth today. thank you again guys.