Solved Configuring RAM with different capacities and cas

Gigabyte motherboard / Ga-h97-d3h
March 5, 2015 at 14:09:04
Specs: Windows 7 64 bit Ultimate, i7 4790 \ 24 Gb's GSKILL 1600 DDR3
Hi,

I just upgraded my memory yesterday. I was running 16 GB (4x4) GSKill Ripjaws X series 1600 cl8.
http://www.newegg.ca/Product/Produc...

I pulled 8 GB (2x4)of that RAM and added 16 GB (2x8) of GSKill Ripjaws X series 1600 cl9
http://www.newegg.ca/Product/Produc...

So the difference is the capacity and the timing. Voltage and speed are the same.

In XMP mode I was able to get it all to run at the rated 1600, and at cl9 - the slower of the two timings, which is what I expected. CPUz shows it also as running dual channel, although if I understand it correctly, this is actually some kind of flex mode.

Here is a screenshot of the settings from CPUz's validation page.

http://s6.postimg.org/7axs7p2gh/CPU...

So the (2x4) 8GB's are in slots 2 & 4 which is actually Channel A, and the (2x8) 16GB's are in slots 1 & 3, which is Channel B (according to the mobo's manual)

There are a couple of things I'm nto sure about though.

1) If you look at the 8 GB sticks in slots 1 and 3 it shows them as 10700, not their rated 12800. They were also recognized this way by CPUz when I tried running that kit without the other (2x4) 8 GB kit added. It shows them as PC3-107000 (667MHz) - so it's recognizing them by default at 1333 speed, rather than 1600. It's only in XMP they run at the rated 1600.

Here is a CPUz screenshot of one 8 and one 4 GB slot as they are now. Notice the difference under 'Max Bandwidth'. The 4 GB stick is recognized correctly; the 8 GB is recognized as 1333 PC 10700.

http://s6.postimg.org/3mcolyhtd/CPU...

Is this just an anomaly with CPUz or is my mobo not recognizing them correctly? or is it that I was sold memory that is slower than rated & what I was supposed to get?

2) Secondly, someone mentioned that to actually get the memory running in dual channel I should be splitting the kits, so I'd be running (8+4) 12Gb in each channel, not the matching kits in each channel. Any opinions on that?

I upgraded because I was running out of memory while editing and having multiple instances of editing programs open. So I tested it as it is now by running programs and increasing RAM usage in Dynamic RAM Preview until I had maxed the 24GB. They system seems rock stable. I'm ready to call it a day, but I wanted to inquire about the two aforementioned things - Was I sold the right RAm, and should I consider splitting the kits to equal two 12GB channels instead of one 16GB and one 8 GB?


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✔ Best Answer
March 6, 2015 at 05:50:33
You're making this way too difficult.

"Dual" means two, correct? You have 2 channels - A & B. To enable dual channel mode, you need to use both channels at the same time. In your manual, the channels are shown as so:

Channel A: DDR3_2, DDR3_4
Channel B: DDR3_1, DDR3_3

And the slots are arranged on your board (from left to right): 4, 2, 3, 1.

If you were to install two RAM sticks & put them side by side in slots 4 & 2, you would only be using channel A, therefore you would be using single channel mode. To enable dual channel mode, you need to use BOTH channels. In other words, channel A + channel B. So the sticks should go in slots 4 & 3.

For your 4 stick configuration, you need 12GB in channel A & 12GB in channel B, plus the pairing needs to be correct (8GB paired with 8GB, 4GB paired with 4GB). Either of these would be correct:

DDR3_4 = 8GB
DDR3_2 = 4GB
DDR3_3 = 8GB
DDR3_1 = 4GB

DDR3_4 = 4GB
DDR3_2 = 8GB
DDR3_3 = 4GB
DDR3_1 = 8GB



#1
March 5, 2015 at 15:46:46
"someone mentioned that to actually get the memory running in dual channel I should be splitting the kits, so I'd be running (8+4) 12Gb in each channel, not the matching kits in each channel. Any opinions on that?"

Exactly right, well, sort of. You should be pairing up the sticks from each kit. The way you currently have them is split. To run dual channel, you need A + B, so either 1+2 or 3+4; or 1+2 plus 3+4. So with your 2 pair of RAM sticks, you should have 8GB sticks in 1+2 plus 4GB sticks in 3+4 (or vice-versa).

message edited by riider


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#2
March 5, 2015 at 16:56:42
Thanks for getting back to me riider

You say: "Exactly right, well, sort of." So I need to get some clarity on this because I'm getting confused. With how CPUz reads slots, my mobo labels slots and what you're saying, I'm not entirely sure what you are calling 1,2, A & B, and referring to as a channel.

My Gigabyte mobo has 4 slots. From left to right starting closest to the cpu, Gigabyte labels them in the manual as 4, 2, 3, 1. As per most mobo's the slots are color coded to make it easier: slots 1 & 2 are grey and slots 3 & 4 are black. So left to right form cpu it goes black, grey, black, grey

However, it also says
Channel A is slots 2 & 4
Channel B is slots 1 & 3
By their labeling, those slots are directly next to each other.


I was under the impression that using paired sticks in the corresponding colored slots would = a channel, and also = running them in dual channel. Am I misunderstanding this? Or is it that the sticks directly adjacent to each other constitute a channel? It would appear so from Gigabytes labeling of Channel A & B shown above.

But if i only had two sticks, Gigabyte recommends running them in the grey slots ,From the manual: "For optimal performance, when enabling Dual Channel mode with two memory modules,we recommend that you install them in the DDR3_1 and DDR3_2 sockets" So from left to right of cpu it it would look like: blank slot, ram, blank slot, ram.

So right now left to right I have 8Gb, 4GB, 8 GB, 4GB As you can see form the pic I posted, CPUz shows this as dual channel. So I'm confused. Are you saying it should be 8GB. 8GB, 4GB, 4GB ? (or 4Gb, 4GB, 8GB, 8GB) with same capacity ram next to each other?

I think what confuses this further for me is that what Gigabyte labels left to right 4, 2, 3, 1, CPUz reads left to right 1, 2, 3, 4 - I'm gathering that from the info it is populating in the slots under the SPD tab


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#3
March 5, 2015 at 17:03:58
Also from the manual: "It is recommended that memory of the same capacity, brand, speed and chips be used ad installed in the same colored DDR3 sockets" which is also why I had them in the 8GB, 4GB, 8GB, 4GB configuration.

Edit:

The relevant page in the manual for reference:

http://s6.postimg.org/eue079pdd/Dua...

message edited by Tim_B


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#4
March 5, 2015 at 19:28:30
Tim: I've read it like you have so that is how I would have set it up if I could not get identical RAM in all slots. I also trust riider so I will wait also for a slightly clearer explanation from him.
As far as the RAM being recognized as slower than advertized, most RAM that is 1600MHz and higher will be recognized as slower until you enable XMP or manually set up the RAM in BIOS according to the specs. I would not worry too much about that as long as they run stable at the better settings with XMP active.

You have to be a little bit crazy to keep you from going insane.


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#5
March 5, 2015 at 19:56:59
Thanks Fingers, for your input and clarifying the speed issue.

Yah I figured it was set up the way the mobo suggests for mismatched RAM, but I'll wait then for clarification from riider as to whether that is even correct and \ or optimal.

If you look at the info from the manual first about the slots they include for channels A & B, then the later info about the placement of the RAM by their color suggestion, there is something that doesn't make sense to me about those two pieces of info taken together. It seems contradictory. For ex. if you only have two sticks installed, and you follow their color scheme, then it seems to contradict the info about Channel A being slots 2 & 4, and Channel B being slots 1 & 3. You'd be apparently placing the two sticks in two different channels, and I would think this would then not be Dual Channel.

I suspect it's just that I'm not understanding all the info properly.

message edited by Tim_B


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#6
March 6, 2015 at 05:50:33
✔ Best Answer
You're making this way too difficult.

"Dual" means two, correct? You have 2 channels - A & B. To enable dual channel mode, you need to use both channels at the same time. In your manual, the channels are shown as so:

Channel A: DDR3_2, DDR3_4
Channel B: DDR3_1, DDR3_3

And the slots are arranged on your board (from left to right): 4, 2, 3, 1.

If you were to install two RAM sticks & put them side by side in slots 4 & 2, you would only be using channel A, therefore you would be using single channel mode. To enable dual channel mode, you need to use BOTH channels. In other words, channel A + channel B. So the sticks should go in slots 4 & 3.

For your 4 stick configuration, you need 12GB in channel A & 12GB in channel B, plus the pairing needs to be correct (8GB paired with 8GB, 4GB paired with 4GB). Either of these would be correct:

DDR3_4 = 8GB
DDR3_2 = 4GB
DDR3_3 = 8GB
DDR3_1 = 4GB

DDR3_4 = 4GB
DDR3_2 = 8GB
DDR3_3 = 4GB
DDR3_1 = 8GB


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#7
March 6, 2015 at 12:18:44
Thanks riider, The light went on, I got it now. It would be too convoluted to explain the part that was tripping me up. But I understand, and so yes, it is configured now properly. Thanks for your help and the explanations.

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