Memory questions

P

Phantoms

Limp Gawd
Joined
Nov 19, 2006
Messages
315
I was reading the thread 2x1GB setup vs 2x512MB + 1 GB setup and saw that adding more memory instead of replacing it may slow a system down. Is the 1T/2T argument mute when it comes to intel cpus? I'm running a Gigabyte 8knxp board (i875) that currently has 1GB (512MBx2 of Corsair XMS). I was planning on buying 2GB (1GBx2) more and adding it to my system to make 3GB total. My current memory has 2-3-3-6 timings and the pair I'd add would have at least as good.
 
Command rate is not adjustable on MOBOs using Intel chipsets. In your case, you are much better suited to buy and use only a 2 x 1gb kit, especially if you are OCing. 4 DIMMs will limit your OC as compared to 2 DIMMs. Also, when adding memory to existing system memory, you need to EXACTLY match the memory in both revision and lots to ensure that you do not mix different types of ICs. Mixing and matching ICs can lead to instability and could possibly not even boot.
 
Mike, I have ordered a set of Corsair TwinX 3200C2PT (1GBx2).

Is there a problem with running different size matched pairs (the TwinX 512x2 along with the TwinX 1GBx2)? Would the instability you mentioned be because of that, or because of having different brands of memory?
 
Mike Clements said:
Command rate is not adjustable on MOBOs using Intel chipsets.
Click to expand...

in his case, this is true.. however it has come to my attention that 965x supports 1T. just most mobo mfg's don't bother putting the option in the bios for whatever reason and default to 2T.

</ot>

the instability comes from the memory controller freaking out when presented with two kits of memory that don't have the same specifications. often, it'll work fine and simply run at the slower of the two sets, but i can't say what'll happen with 2x1gb + 2x512mb.. never tried it on an intel setup before.
 
Both sets will have 2-3-3-6 timings and both are the same series of Corsair TwinX modules, just one pair is 512x2 and one pair is 1GBx2.

My MB is a gigabyte 8knxp and has 6 memory slots, but only four are usable if you want dual channel. Am I correct in that I would put the 1GB modules in slots 1 and 3 (first channel) and the 512mb modules in slots 2 and 4 (second channel)?
 
You have the channels correct but, you do have some potential for instability. You are mixing 2 different densities of ICs in this case and 2 totally different ICs at that. Also, the simple fact of 4 DIMMs means more inherent latency in the system.

If you are unstable at your preferred settings above, try 2.5,3,3,7 for the timings and set the Vdimm to the 2.75v to 2.9v range.

Eclipse, where are you seeing that Intel chipsets (965 only???) are supporting 1T command rate? I have not seen this yet.
 
Nope, on your mobo for dual channel you'd have to install like this:

Channel A = dimm1,4
Channel B = dimm2,5

You can use all six dimms in dual channel, but the population rules get a bit hairy plus they may not function at ddr400 speeds due to chipset limitations. I'm curious if using the different sized modules will even work. Anyway, I hope this helps a little.
 
With the bios as unstable as that article describes, ABIT should have just omitted that setting IMO. I would personally like to see ABIT make a solid comeback. However, the last 2 boards I have had from them (prior to my current IN9 32X MAX) had poor bios' and also lacked proper bios revisions. Also IMO, they should focus on making a bios stable before enabling every feature under the sun.
 
Sir Lion you are correct. I mistaking stated slots thinking four slots.

Slots 1 and 4 are correct for channel A. However, my manual states that I can use either 2 and 5 or slots 3 and 6 for Channel B. It states that I can only have two channels for dual channel to work, but I don't know.


Another question. Would I stack the mem as a set on each channel such as A-1024x2, B-512x2 or would I mix it such as A-1024,512, B-1024,512? This using the above that A is slots 1 and 4, B slots 2 and 5. I'm inclined to believe the first way, am I correct?
 
Mike Clements said:
With the bios as unstable as that article describes, ABIT should have just omitted that setting IMO. I would personally like to see ABIT make a solid comeback. However, the last 2 boards I have had from them (prior to my current IN9 32X MAX) had poor bios' and also lacked proper bios revisions. Also IMO, they should focus on making a bios stable before enabling every feature under the sun.
Click to expand...

i agree wholeheartedly, but the option is there, which means the chipset has support for it :D
 
Phantoms said:
Sir Lion you are correct. I mistaking stated slots thinking four slots.

Slots 1 and 4 are correct for channel A. However, my manual states that I can use either 2 and 5 or slots 3 and 6 for Channel B. It states that I can only have two channels for dual channel to work, but I don't know.


Another question. Would I stack the mem as a set on each channel such as A-1024x2, B-512x2 or would I mix it such as A-1024,512, B-1024,512? This using the above that A is slots 1 and 4, B slots 2 and 5. I'm inclined to believe the first way, am I correct?
Click to expand...

As I've said before, I'm not sure if it'll work, but if it does, it would be the first way you mentioned.
 
Got the 1GBx2 TwinX memory today and installed it in slots 1 and 4, moved my 512x2 TwinX into slots 2 and 5, went into BIOS and set them up as 2.5-3-3-6 (MB doesn't have a 2 CAS setting), fired up the system and everything runs fine. I fired up MS FSX which really taxes a whole system, not just one part, and flew a heli for about an hour.

Glad to report no problems, system is running great. BTW, I do have a slight overclock (420 bus from 400 stock, 3.2P4 running at 3.37). I had this slight OC for a while before installing this new memory.

Thanks Corsair for great, solid memory.
 
Great news man, and I am glad it worked. It doesn't always so you were one of the lucky ones! :cool:
 
You must log in or register to reply here.
Back
Top