multi-core CPU and Memory optimization

---

I've been listening to the A+ certification classes and I have a general machine setup question. Lets say I have a quad core CPU on a theoretical motherboard. (no particular brand) would I get better performance if I were to populate the memory with 1 16GB stick of memory, or with populating all four memory slots with 4 GB sticks of the same speed memory?

David,
I'm going to make the assumption that there are alot of smarter hardware guys than myself out here than myself. But I will give this a stab and others can say how wrong I am about this

On most Motherboards today, they operate on dual or more channels for RAM. If so, My assumption is going to be accessing multiple channels simultaneously is going to give you faster performance than a single channel being accessed multiple times.

Remember than speed on the computer is normally about how much can be done at a given time rather than how fast any one component can do things.

So in your instance, if you have a single stick of RAM (16GB) connecting to a single a channel running at 3.1 GHz that's FAST! But if you take 4 sticks (=16 GB) at the same speed but can be accessed at the same time. Your speed didn't increased but you're able to do more in the same amount of time.

Cordially,
Ronnie Wong
Host, ITProTV

David - I saw your post within a minute of you making it, and like Ronnie, had the apprehension of answering it early. I'll build on Ronnie's answer for your scenario to suggest the middle ground: two 8Gb 'sticks' to make 16Gb of RAM. Later expansion (it is hard for anyone to envision 32Gb of RAM, more so for me - starting - and still having - a system with 16Kb of RAM expandable to 64Kb!) could be to add two more 8Gb 'sticks', although it is more common to start fresh nowadays rather than to upgrade existing equipment.

Thank you all very much. I had suspected as much and as a rule I always install memory in pairs and leave room for expansion, but after listening to how the multi-core accesses memory video I had gotten the idea that each core would work better with a dedicated memory stick (so to speak) rather than sharing time with one. I was mostly trying to apply what I think I learned to a real world experience.

I haven't watched the video, but the cores share access to the system RAM. So the number of cores isn't important for the memory configuration; the number of channels is. Dual channel memory controllers are popular today; memory modules for them are best installed in pairs. But high end systems may have triple or quad channel memory controllers. Memory for them should be installed multiples of 3 or 4. Again, this is independent of the number of cores.

Each core generally has its own dedicated L1 cache memory, but that's on-chip. It has nothing to do with system RAM configuration.