Considering only performance, nothing else (price, future, etc.), what would be the best choice?
I know I'd use 4 x 1 gb, but that's not my question... I just wonder what's faster between those options
In dual channel.
Dual channel works best with two sticks , so I'd say the 2 x 512mb is better.
I would also prefer just one stick of 1GB, less hassle with timings having to match another stick. If one stick is out by abit , it will give you nothing but trouble.
2X512 MB if you can run it in dual channel. Sometimes having 4 sticks causes the timing to have to be slowed down, which is a big impact on performance. My brother tried going from 2 GB (2 sticks) to 4 GB (4 sticks) and it was slower with that amount of memory. Now if you have a very memory hungry application having more slower memory is still better than paging to disk. Here is one utility that you can use for testing memory performance: