8,8,8,24 and 9,9,9,24 memory mix ?

[gerry410]

Hi all, I have a triple channel 3 x 2 6GB set of Corsair Dominator memory (CMP6GX3A1600C8).
I want to add a set of CORSAIR DOMINATOR 12GB (3 x 4GB) (12800) CMP12GX3M3A1600C9.

The timings on the new 3x4 12GB set are 9,9,9,24.
Older sticks timings for the 3x2 (6GB) set are 8,8,8,24.
Both are 1.65 volts and DDR3 1600.

I understand I can relax the timings on the 8,8,8,24 6GB set but I'm not sure how to start.

Should I install :

1) the 8,8,8,24's and relax the timings to 9,9,9,24 then add the 12 GB set.

or

2) Install the 12GB 9,9,9,24 set first then the 8,8,8,24 6GB set?

I don't know what are the cautions I should take.

Thanks all

 

[rolli59]

It is safest to relax the timings first, then there is no conflict.

 

[gerry410]

It is safest to relax the timings first, then there is no conflict.

Install the faster sticks first, relax them to 9.9.9.24 then install the 12 GB set?

 

[gerry410]

Hi all, I have a triple channel 3 x 2 6GB set of Corsair Dominator memory (CMP6GX3A1600C8).
I want to add a set of CORSAIR DOMINATOR 12GB (3 x 4GB) (12800) CMP12GX3M3A1600C9.

The timings on the new 3x4 12GB set are 9,9,9,24.
Older sticks timings for the 3x2 (6GB) set are 8,8,8,24.
Both are 1.65 volts and DDR3 1600.

I understand I can relax the timings on the 8,8,8,24 6GB set but I'm not sure how to start.

Should I install :

1) the 8,8,8,24's and relax the timings to 9,9,9,24 then add the 12 GB set.

or

2) Install the 12GB 9,9,9,24 set first then the 8,8,8,24 6GB set?

I don't know what are the cautions I should take.

Thanks all

 

[nikorr]

Whats your mobo?

 

[rolli59]

Yes.

 

[Pinhedd]

Mixing DIMMs with different DRAM timings is usually a very bad idea. A set that is stable at 8-8-8-24 will not necessarily be stable at 9-9-9-24. Most of the time it will be, but not always. It might not even run at 1600 anymore. If you want to go ahead and try this the system should automatically select the most appropriate timings on POST (which based on your setup will probably be JEDEC timings for 1333 and not 1600). In the worst case you simply ditch the 6GB set and use the 12GB set

 

[nikorr]

This next topics has been merged by Nikorr
■ Adding more ram

 

[gerry410]

Whats your mobo?

Asrock x 58 extreme and core i7 930. all that info is under my "more info"
So I think what everyone is saying is install the 6gb c8's first relax the timings to 9,9,9,24 (and i do that in the bios ram timings)and then add on the 12 gb set and hope they play nice together. Is that correct?

thanks everyone

 

[Pinhedd]

Asrock x 58 extreme and core i7 930. all that info is under my "more info"
So I think what everyone is saying is install the 6gb c8's first relax the timings to 9,9,9,24 (and i do that in the bios ram timings)and then add on the 12 gb set and hope they play nice together. Is that correct?

thanks everyone

What you should do first is set the 6GB set to 9-9-9-24 and test it thoroughly using memtest. Loser timings does not guarantee stability. Next, separately install and test the 12GB set at the 9-9-9-24 timings independent of the 6GB set. Finally, install and test both sets. The reason I suggest doing is that you're breaking a number of rules:

First, you're mixing two different sets of DIMMs with different recommended timings. Most memory controllers and chipsets require that all DIMMs on each channel have the exact same timings on all channels while in operation. If the same timings are supported on both sets of memory via SPD this usually isn't an issue. Some such as the X79 and Rampage IV Extreme allow for timings to be configured on a per-channel basis but this is not at all recommended for every day use. See above where I said that loosening timings will not necessarily guarantee stability. DRAM is complicated, this is the consequence.

Second, You're running more than 1 DIMM per channel and by definition more than one rank. More than one rank means more than one chip select which means increased electrical load which increases latency. Usually the latency increase isn't so bad that it necessitates loosening timings further but on occasion this isn't the case. This is why Intel's specification for most processors that do support 1600Mhz memory IO only officially support one DIMM per channel for 1600 and 2 for 1333. 95% of the time this isn't a problem with DDR3 but I had lots of problems with DDR2 doing exactly this. It's the 5% that end up here on Toms asking for help.

Good luck

 

[gerry410]

What you should do first is set the 6GB set to 9-9-9-24 and test it thoroughly using memtest. Loser timings does not guarantee stability. Next, separately install and test the 12GB set at the 9-9-9-24 timings independent of the 6GB set. Finally, install and test both sets. The reason I suggest doing is that you're breaking a number of rules:

First, you're mixing two different sets of DIMMs with different recommended timings. Most memory controllers and chipsets require that all DIMMs on each channel have the exact same timings on all channels while in operation. If the same timings are supported on both sets of memory via SPD this usually isn't an issue. Some such as the X79 and Rampage IV Extreme allow for timings to be configured on a per-channel basis but this is not at all recommended for every day use. See above where I said that loosening timings will not necessarily guarantee stability. DRAM is complicated, this is the consequence.

Second, You're running more than 1 DIMM per channel and by definition more than one rank. More than one rank means more than one chip select which means increased electrical load which increases latency. Usually the latency increase isn't so bad that it necessitates loosening timings further but on occasion this isn't the case. This is why Intel's specification for most processors that do support 1600Mhz memory IO only officially support one DIMM per channel for 1600 and 2 for 1333. 95% of the time this isn't a problem with DDR3 but I had lots of problems with DDR2 doing exactly this. It's the 5% that end up here on Toms asking for help.

Good luck

Hi pinhead and thanks for your help. So I guess I should have followed my first inclination and purchased a second set of exact match ram. I was going to to that but someone here at toms suggested the 12 gb set was better for 20 bucks more and that I could "easily relax the timings on the old set". Hmmmm. Live and learn.

I will take your advise and test both sets independently then try to find the happy median settings for both to run together.
Changing timings on the memory is a new ball park for me.
I have my processor over clocked from the stock 2.8/1066 to 3.6/1440 and 3.8/?? (i forget) respectively but changing timings on the memory is a new ball park for me. I have some reading to do then will proceed with caution.
Any more advise feel free please. i owe u a beer.

 

[rolli59]

You have the new set, couple of options relax the timings on the old and try running the new with it over 90% chance of it working fine since both are the same voltage. Other option is just run on the 12GB set and you got 6GB upgrade and sell the old ram on ebay.

 

[Pinhedd]

Hi pinhead and thanks for your help. So I guess I should have followed my first inclination and purchased a second set of exact match ram. I was going to to that but someone here at toms suggested the 12 gb set was better for 20 bucks more and that I could "easily relax the timings on the old set". Hmmmm. Live and learn.

I will take your advise and test both sets independently then try to find the happy median settings for both to run together.
Changing timings on the memory is a new ball park for me.
I have my processor over clocked from the stock 2.8/1066 to 3.6/1440 and 3.8/?? (i forget) respectively but changing timings on the memory is a new ball park for me. I have some reading to do then will proceed with caution.
Any more advise feel free please. i owe u a beer.

I think you made the right choice by buying a 12GB set rather than another 6GB set. If you had bought the same 6GB set you'd still have 12GB of RAM but with the 12GB set you'll have 18 if all goes well.

 

[gerry410]

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I think you made the right choice by buying a 12GB set rather than another 6GB set. If you had bought the same 6GB set you'd still have 12GB of RAM but with the 12GB set you'll have 18 if all goes well.

Hello again, Mr Pinhead. I hope you don't mind me bothering you again but your advise was very helpful and I was hoping you could review my results. I think all is well the different memory modules seemed to blend well together. I now have the computer oc'ed to 3.8 and it's stable.
I ran memtest for both sets individually then together for 2 passes.
I'm not sure why my "computer info says only 16gb useable is there a problem with that?

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[Pinhedd]

Could you post a picture of where it says that on 16GB is usable?

 

[gerry410]

Could you post a picture of where it says that on 16GB is usable?

[img=http://img213.imageshack.us/img213/7817/16gbusable.th.jpg]

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I've never used image shack before. I'm trying the different options.

Next to "Installed Memory (Ram): 18.0 GB (16.0 GB usable)

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[Pinhedd]

Interesting

I've never run into that myself but several other people here on Toms have. It turned out to be that one of the DIMMs wasn't seated right.

Start pulling out your 2GB DIMMs one by one until that goes away

 

[gerry410]

Interesting

I've never run into that myself but several other people here on Toms have. It turned out to be that one of the DIMMs wasn't seated right.

Start pulling out your 2GB DIMMs one by one until that goes away

OK, I will try that.
I was thinking of that but then thought to myself if its posting the 18GB in Memtest85, the BIOS and in my "System Profile", maybe it was a problem with the timings.
Do you think my timings are set correctly?
After sending the the last message I changed the "Command Rate from 2T to 1T. The computer seems to be working perfectly.

 

[Pinhedd]

Strange. 1T is by definition less stable than 2T (command rate is the number of clock cycles between chip select and the command). If it works with 1T, all the better

 

[gerry410]

Strange. 1T is by definition less stable than 2T (command rate is the number of clock cycles between chip select and the command). If it works with 1T, all the better

I just switched all the ram sticks. I rotated 1 to 3, 2 to 1, 3 to 2. It still reads 16 of the 18 usable. I'm wondering if it maybe one of the Ram sockets is faulty. Although all six are posted in memtest.

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[Pinhedd]

It's possible that one of the sockets is faulty which is why I recommended yanking the 2GB sticks one by one until it stops saying that 2GB is unusable.

The only way to solve this is to experiment

 

[Pinhedd]

Nevermind all that. I see what your problem is

Windows 7 Home Premium is limited to 16GB for marketing reasons. You will need to obtain professional or Ultimate to use more

 

[gerry410]

Nevermind all that. I see what your problem is

Windows 7 Home Premium is limited to 16GB for marketing reasons. You will need to obtain professional or Ultimate to use more

Well isn't that something! I just finished isolating what I thought was the bad socket (#5), the last 2 GB. LOL I guess I will have to be satisfied with the 16 GB. It really doesn't make a noticeable difference to me, my computer runs like a rocket. It being my first build everything is a learning experience. This is another lesson. I'm not a big gamer but I do want my systems performance to be as good as possible.
Again, I want to thank you for all your time and friendly advise and I wish you and your family all the best.

 

[gerry410]

Best answer selected by gerry410.

 

[Pinhedd]

Thanks. If you ever have any other problems feel free to open a new thread or PM me