Sure...it has to do with the chunks of information that get sent to the memory and also how it works with the Virtual Memory-the swap/page file. The way that the motherboard sees and reads the chips as well is a key factor to this as well. Because the larger memory chips will take up more priority and want to take the larger chunks of information first before the smaller RAM chips. At first I didnt think that was the case when I first started building and repairing PC's...then I learned my lesson!!!!
I used to get this wierd crackling and odd performance issues...I reordered the ram one day and what do you know..the crackling went away...put the ram back unordered and crackling came back...so you seee, priority goes to the larger chunks first so you put them in that order and the system will run mor efficient that way
Opus

Thanks,
I recently added a single 256 board to the 3x128 that were already in their and was sure that performance had got worse but couldn't figure out why. I'll give this a try
-Peter