Questions regarding Dual Channel RAM.

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manowar

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Hi all,

I've done a lot of research regarding Dual Channel RAM. However, there is a few "grey areas" which I'm a little unsure about.

1. Does RAM have to be Dual Channel certified in order to run in Dual Channel mode? For instance, If I picked up two sticks of PC3200, the same model and speed, but not sold has a matched kit, would there still be a possibility that it would run in dual channel mode?

2. Secondly, my motherboard has four DIMM slots, 2 blue and 2 black (channels A and B). What would happen if I placed two matching kits, but one kit was PC3200 and one kit was PC2700 into the DIMMs? Would I still achieve Dual Channel mode, since the kits are installed on two seperate channels (A and B) or does both channels have to be running exactly the same speeds i.e four sticks of say PC3200?

3. Thirdly, I know the overall goal regarding Dual Channel is to achieve an 128-bit data path from the Memory controller to the RAM - however, if my motherboard has four slots, and I only fill two of them with a matched kit of RAM - am I still achieving 128-bits, or 64-bits? Or would all four DIMMs have to be populated (both channels)? If all four DIMMs are populated (Channels A and B) - then how does that work? Do the two channels run on two seperate 128-bit data paths or is it divided between the two 64x2=128?

Cheers all.
 
1. No. They must be Dual Channel Certified. Just getting any 2 sticks will not give you Dual Channel.

2. The PC32000 would run at the PC2700 speeds. You would lose the extra speed from the PC3200. Yes you would reach dual channel mode but as stated you would lose the extra speed.

3. No you would reach the 128. It is 128 per Dual Channel setup. Not 128 with all 4 sots filled.
 
3. No you would reach the 128. It is 128 per Dual Channel setup. Not 128 with all 4 sots filled.

So are you saying that if I filled all four slots - I'd have two seperate 128-bit data buses? One on Channel A and one on B?
 
Yes in theory you should. It may also work like this.

When only 1 set of dual channel RAM is in use it uses teh full 128 Bus. But when you get 2 sets of Dual Channel RAM each set uses 64 Bit to give you a total of 128.

There are many combinations of what can be done. It all comes down to how your Mobo is setup.
 
Cheers Mak123.

Hey, out of interest. Are you a fan of Highlander? I noticed your location is "The Source" :D
 
Reference to The Matrix. The Source being the Mainframe. ;)
 
Reference to The Matrix. The Source being the Mainframe. ;)

Ah, I thought you meant The Source as in Highlander: The Source. :)

One last question. I've read that some motherboards don't agree with double or single sided RAM (chips) - whats the idea behind that? From what I know, the amount of chips determines the capacity of the RAM?
 
While yes that is true the chips themselves can be either single sided or double sided to reach the capacity that they are.

So to have a single sided 2GB chip would be different than a 2GB double sided chip. The idea behind it is that you can use less material to achieve the 2GB double sided since you are utilizing the full RAM chip instead of just a single side of it.

Since the single side will not have as many connections available as teh double sided chip does.

At least this is my understanding of the whole thing. I could very well be wrong. ;)
 
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