A question about RAM

Some time back I had read that 2x512 modules are faster that 1x1024 module. Would going with 4x512 rather than 2x1024 be faster in dual channel?

Go for 2x1024

No. Apart from the fact that few motherboards can run 4 sticks, they generally will run them at slower timings (2T vs 1T). 2 sticks is always faster than 4 for this reason, and because with 4 sticks there’s more physical addresses for the memory controller to map. The exception might be 4 sticks of single-sided RAM, which are near impossible to find.
It’s also good to note that most of the differences are only seen in benchmarks. The benefits and speed advantages of MORE RAM far outweigh any potential drop in memory speed due to having more. 2x1024 is still over-kill for 99% of users. The main reason why 2x512 is faster than 1x1024 is because of dual channel, but the difference again is pretty small.

Hi CDan, I agree that for most applications 2GB or RAM is over kill, but there are some video editing and CAD programs that would benefit the extra RAM. I suspect that this is going to be especially true with Vista.

My question was specifically about dual channel, so let me see if I have this right. The only reason that I would want 2x512MB rather than 1x1024MB is so that I can run dual channel. I’m correct in understanding that 2x1024 in dual channel would be faster than 4x512 in dual channel?


I’m correct in understanding that 2x1024 in dual channel would be faster than 4x512 in dual channel?

Yes, assuming your MB can even run 4 sticks (don’t be fooled by those 4 slots), it will probably run 4 sticks at slower timings, and many boards are just unstable with 4 sticks. The newer x64 AMD processors with the memory controller on board are more stable and often will run 4 sticks pretty well, but the speed hit with the slower timings can run as much as 10%. Depends on the board. Some boards will even default to 333MHz with 4 sticks.

2 sticks is 4 rows of memory chips, 4 sticks is 8 rows. The more rows you have, the slower it will read and write to them. There are such things as single-sided DIMMS, but they are very rare. Most are now double-sided. (row of chips on both sides.)

I use 2 sticks of 1024, and even when burning DVD’s or crunching huge video files, there’s always loads of free RAM, never less than 800MB and usually more like 1100.

Given current pricing however, 2x 1024 can be the same price as 2x 512.

Thank you for the information CDan, I understand now.