Dual channel Memory question

[impreza]

I have a 1gb and 512mb memory sticks, If I replaced the 512mb with another 1gb of the same manufactor would it run dual channel? If not is it worth replacing it all with 2 new 1gb sticks to run dual channel?

 

[Dante_Jose_Cuervo]

That depends on whether or not a) your mobo supports it and b) your CPU supports it.

What mobo and CPU are you using?

 

[purdueguy]

Unless I stand corrected, dual-channel has nothing to do with the CPU. At least with modern CPU's. I'm not talking about a PIII or AMD K6-2. I thought it was strickly a motherboard issue. If the mobo supports it, then you don't have to worry about what chip you are using.

Dual-channel from Dell. Dope, I just said the "D" word.

 

[thelvyn]

It only depends on the cpu as far as what socket it is.
Socket 754 for example does NOT support dual channel while socket 939, AM2, 775 etc do support dual channel.

 

[purdueguy]

Socket A had dual-channel support (at least my mobo) but yet Socket 754 did not. Another reason to stay away from Socket 754.

You learn something everyday. Thanks for the clarification.

 

[nukemaster]

Socket A had dual-channel support (at least my mobo) but yet Socket 754 did not. Another reason to stay away from Socket 754.

You learn something everyday. Thanks for the clarification.

754 is long dead....and it had no dual channel becuase at the time it did not need it....due the the IMC.....shame that 754 went squish so fast....

 

[nobly]

Another thing - you need 2 memory modules of the same size and speed. You can't have dual channel with just one memory module.

 

[Mondoman]

... you need 2 memory modules of the same size and speed and same internal organization. ...

 

[nobly]

... you need 2 memory modules of the same size and speed and same internal organization. ...

I don't know what you mean by internal organization. Do you mean low vs high density RAM? Or double vs single sided?

Here are rules for dual channel, from intel:

Rules to Enable Dual Channel Mode
To achieve Dual Channel mode, the following conditions must be met:

* Matched DIMM configuration in each channel
* Same Density (128MB, 256MB, 512MB, etc.)
* Matched in both Channel A and Channel B memory channels
* Populate symmetrical memory slots (Slot 0 or Slot 1)

Note: Configurations that do not match the above conditions will revert to Single Channel mode.

The following conditions do not need to be met:

* Same brand
* Same timing specifications
* Same DDR speed

Note: Memory channel speed is determined by the slowest DIMM module populated in the system.

http://www.intel.com/support/motherboards/desktop/sb/cs-011965.htm

Speed here doesn't apply because the memory will probably downclock itself to the most common denominator between the memory modules. (e.g. a 333Mhz and a 400Mhz DDR modules will work in dual channel, but at 333Mhz - the 400Mhz will downclock to 333Mhz).

 

[Mondoman]

I don't know what you mean by internal organization. Do you mean low vs high density RAM? Or double vs single sided?

yes and yes.

Here are rules for dual channel, from intel:
Rules to Enable Dual Channel Mode
To achieve Dual Channel mode, the following conditions must be met:

* Matched DIMM configuration in each channel
* Same Density (128MB, 256MB, 512MB, etc.)
* Matched in both Channel A and Channel B memory channels
* Populate symmetrical memory slots (Slot 0 or Slot 1)

Note: Configurations that do not match the above conditions will revert to Single Channel mode.

The following conditions do not need to be met:

* Same brand
* Same timing specifications
* Same DDR speed
...

Certainly different manufacturers will have different designs that give different levels of leeway. The Intel design above is very accomodating. My Athlon notebook, OTOH, won't run in dual channel mode even with a pair of SODIMMs of same capacity and organization. They differ in speed and in latency, however. YMMV.

 

[nobly]

I don't know what you mean by internal organization. Do you mean low vs high density RAM? Or double vs single sided?

yes and yes.

I agree with you! Usually I find that this is motherboard dependent and is usually documented in the motherboard manual.

Interesting that the notebook wouldn't run in dual channel.

YMMV, indeed.

 

[RyanMicah]

So did they answer your question? You need two ram sticks to have dual channel. Without going into details that I don't even understand, dual channel means two sticks. They need to both be PC3200 or whatever you desire if you can help it, brand doesn't matter, and you should have the same amount of ram in all the slots you fill. Also, if you have 4 slots, make sure the sticks are spaced with a slot in between, putting your first stick in the slot closest to the processor. Dante asked you the most important thing out of all the replies "What is your CPU and your Motherboard?" The reason this is most important is because depending on the cost of ram, adding ram may not even be with your time and money. Other considerations might be to save up a bit more and getting a newer system altogether.

 

[Mondoman]

Ryan, although the suggestions you made above are often correct, they're not always.
The idea behind dual channel is that two memory controllers divide the memory between them, and each works on its half only. This means both can always work at the same time, doubling the amount of data transferred to/from memory in every time period. Some MB designs are very picky, requiring that DIMMs be used in identical pairs, so each memory controller can access exactly the same type of memory. Some, such as the Intel design above, give lots of leeway, only requiring that the total amount of memory each controller accesses be the same, but allowing different mixes of module sizes/designs/etc, as long as the total for each controller (channel) is the same.
If the OP has a MB with strict requirements, he'll need to buy 2 new modules to use for dual channel to work. If the requirements are loose like with the Intel, then replacing the 512MB with a 1GB module will work fine.

 

[impreza]

I have a A8N-E motherboard and a amd 4200+x2 cpu. Do you just need two memory chips the same size and same mhz? or do they have to be identical and have to buy them at the same size?
Thanks

 

[Dante_Jose_Cuervo]

Looking at your mobo it says that you have dual channel. You can use dual-channel on here yes, but 1) it's a good idea to match the stick according to size and latency. 2) try to match brands. Anyways yeah, hope that helps and good luck!

 

[thelvyn]

Without having that mb myself I cant say for sure but its a safer bet to just buy a matched set. It might work if you just buy 1 more of the same size but you wont know till you try.

 

[Mondoman]

Your MB manual and/or tech support will know the answer. We're just guessing.

 

[RyanMicah]

I have a A8N-E motherboard and a amd 4200+x2 cpu. Do you just need two memory chips the same size and same mhz? or do they have to be identical and have to buy them at the same size?
Thanks

Your motherboard may only require one stick of memory. Even though my 3500LL Pro ram sticks came packaged together and are recommended for my Asus A8N-32 SLI Deluxe mobo, I split my ram up and put one in my other system (uses an Asus A8N-VM CSM board, yes that ram will work on it if anyone wondered!)
If you're considering buying ram, you should probably get just what you need, as hardware changes so fast. A 1 gig stick or 2-512mb sticks may be enough. If you do get a 1 gig stick you can always add 3 more later for a total of 4gigs, but sometimes two 512 sticks can be accessed a tad faster by your mobo. I generally buy more ram only if a certain game requires it or if my system is running slow (accessing paging file a lot). Today's standard is probably 1 gig, Vista may tax your system even more if you decide to get it. Odds are though, your system will run on only 256mb's of ram. I was actually able to turn my paging file off on my system with a 1 gig ram stick, although when I put in 512 of PC2700 ram the computer failed to boot without the paging file available.

 

[thelvyn]

Two dimms are not required on any consumer level board.
1 Dimm is all you HAVE to have.
If he wants dual channel then two dimms are required.

 

[RyanMicah]

Two dimms are not required on any consumer level board.
1 Dimm is all you HAVE to have.
If he wants dual channel then two dimms are required.

Ya think? Now you're just stating the obvious. We went over that already. But clarification is always good. I don't pretend to be an expert, I just try to help by saying what I think or have read elsewhere. If I'm wrong I'm happy to accept criticism by someone who knows more.

 

[thelvyn]

You said

Your motherboard may only require one stick of memory.

You seemed to be suggesting that dual channel mode was possible with only 1 dimm.
So I felt it necessary to clarify that.
I have been building my own computers since my 286 so I believe I know what I am talking about

 

[RyanMicah]

Ooh, big man on campus. Alright, well I didn't mean to imply anything. I'm 26, and was technologically deprived as a child. I didn't get a nintendo till I was 14 and a computer in the house till I was in my mid teens. My experience was limited to wordperfect starting in 6th grade, and then in HS I took every comp class it had to offer, mostly programming. Hardware is my new "bag" and I'm learning as fast as I can. I bought a crappy Dell a few yrs ago and recently I researched a lot online and built a couple 64 bit systems. Just trying to offer what info I can to other newbies like me.

 

[thelvyn]

You do realize that if your using a socket 939/940 board and you only put one of those dimms in your depriving yourself of some performance right ?
Potentially a lot as you really need at least 1gb for good performance these days. Pretty soon we are gonna need at least 2gb at the rate things are going.

Yea im an old timer. I remember when the 486dx2-66 cpus came out and I got one for a steal. only $700 dollars with a mb.

I wasnt biting your head off anyway you know ?

 

[RyanMicah]

How well can you explain overclocking? I have 2-1 gig sticks and am getting more soon. They're about 300 for a pack of 2. I don't think my ram is running at top speed as it is. I noticed a significant performance decrease in Oblivion when I took out 1 stick. Although my frame rate is also limited by my overclocked 7800 GT (256mb). I should mention too that my CPU is an AMD X2 4200+ which runs at 2.2 ghz. I've got a fair amount of devices on this comp, although everything is shut down in bios that I'm not using, like serial ports etc. Does this PM thing work and would you like to help me OC a little?

 

[thelvyn]

Try reading this http://forumz.tomshardware.com/hardware/Guide-overclocking-A64-ftopict126122.html