Hi, I'm running 2 matching 512 MB PC 2100 Low Density sticks in dual channel mode. I want to fill my other 2 slots and I'm not certain if I can change to 1 GB sticks to get up to 3GBs on the system or am I better off to just get 2 more 512 MB sticks to match the other channel. I don't know for sure if I can get say PC 2700 or 3200 sticks for the other channel and be OK? Or again, would I be better off to just keep everything the same. The manual says that I can MIX the Density between channels. So I'm "assuming" they are refering to High Density and Low Density chips. Or are they refering to Single sided and Double sided ram sticks. (Or is this actually the same as LOW and High density?) They say "System Density" in the graphic diagram and show the "storage" i.e. 256 mb to 1GB for single dual channel setup and 512mb to 4GB for double Dual channel setup. This is just a little confusing to me. Any help would be greatly appreciated. I've been putting my own personal computers together since I was first asked whether I wanted "Expanded" (More Expensive) or "Extended" memory. It says that I am running in Dual Channel mode right now with the two matching ram sticks. I know that for dual channel to work properly you DO need to have matching sticks in the two banks that interleave with each other. What I'm NOT certain about is whether the two Dual Channel banks need to match in order work correctly. As in, if I have only 1 GB in the first dual channel setup and 2 GB in the other dual channel setup, will these dual channels try to interleave with each other on the main board and have bottleneck issues due to the difference in memory size? If so, then any difference in density and speed would affect this as well correct? Thanks in advance for any help on this. Sincerely, Info Hound
If I remember correctly, for dual-channel to work properly on AMD CPUs, all occupied banks must have the same memory size. That means if Bank A has 2 GB of memory, then Bank B must also have 2 GB of memory. Please correct me if I'm wrong as some memory controllers allow different memory sizes. In such controllers, if you have 2 GB in one bank and 1 GB in another bank, then dual-channel works only for the first GB in both banks. The extra GB of memory in the first bank will only run in single-channel mode.
According to the manual, they can be of different "memory" density for single channel, but need to be the same for dual channel mode. This of course means that my PC 2100's in the A and B banks are running in dual mode. (CPUz confirms this.) But it would "SEEM" that I could put the PC3200, as Chai suggested, in the other A & B banks for the other dual channel and be OK. I'm just not sure if each dual channel operates independently or if they too interleave with each other like each bank within the dual channel does. If they do interleave with each other then there is going to be some kind of a bottle neck or the faster channel will be waiting on the slower one. This too would affect whether there would be an advantage to putting two 1GB sticks in the other channel as well. It's my back-up system that I use when my main Win7 RC system is doing back-ups or virus scans. So, I'm just looking to give XP Pro SP3 a little more head room so it can handle things a little faster for now. I'm sure that just adding another 1GB total will help since it is usually running with 650 MB of ram being used normally and gets up to around 900MB with multiple browser windows open and some torrent downloads going on. If I were to DUMP the Symantic Endpoint Protection I'd free up around 350 MB of ram right away. (That program is a SERIOUS resource hog!! But I've gotten use to it over the last couple of years. It won't run in Win7 though.) Thanks guys for your help and input. Sincerely, Info Hound
Oh, of course. You only need to worry about memory "density" or "size" if you want to benefit from dual-channel mode. Dual-channel mode is different from interleaving. In dual channel mode, the memory controller can read from both channels at the same time, doubling its thoroughput. Interleaving is different - one channel is read at one time, interleaving only reduces some delays. Yes, you are right in that. Very often, the AMOUNT of memory is far more important than the SPEED of the memory or the memory bus.
Thanks Since it is just my back-up system I think I will install another matching pair of PC2100 512MB sticks and be done with this. Unless a I find a REALLY GOOD deal on 4 sticks of 1GB PC3200!! I really do thank you and Chai for your help and qucik replys to this. Sincerely, Info Hound
I think DDR modules are really expensive if compared to DDR2, so unless you can find a really good deal, I think it's going to cost a lot.
When you guys also add in that I use Low Density RAM in my systems it really does get to where I think to myself, "Hmm........is it really worth it or should I just cough up another $150.00 and pick up a replacement tower that's being phased out by like Best Buy?" As always, thank you guys for your input. Sincerely, IH
