[SOLVED] Looking for a memory expert to assist.

[Henties]

Hi all that are capable to assist me with memory configuration on my Skylake build.
I recently had a memory module fail on this mobo that used to be configured with 4 x 8 Gig sticks of one manufacturer and identical speed range. When suddenly one of the sticks failed I replaced the faulty stick as well as one good stick with 2 x 16 Gig Corsair Vengeance modules as listed per the buyers guide of this forum. The replacement sticks have the same speed range of my original sticks but are not of the same manufacturer. Total memory installed is consequently 2 x 16 Gig plus 2 x 8 Gig, yielding a total o 48 Gig. When I install this memory so that it should perform in dual channel mode, as per the manufacturers instruction, my rig becomes unstable and reboots out of the blue whilst I am using it. When I then install the memory as per attachment "Working memory layout 1" as reinforced per attachment "Working memory layout 2" I have a stable and usable computing platform. This working memory configuration, depicted in the mentioned attachments is however not consistent with what the manufacturer considers to be dual channel mode, and I certainly would agree, but it works and the rig is stable during operation.
When now moving to Windows and I interrogate my memory status with CPU-Z it says channel "Dual" does it actually mean that the memory is operating in dual channel mode or is it perhaps operating in "flex mode"? Attachment "Windows CPU-Z. Output" refers. What is actually going on. kindly assist ?
I would really appreciate some expert input on this topic.

Greetings

 

[Jamesbond007]

Hi all that are capable to assist me with memory configuration on my Skylake build.

I recently had a memory module fail on this mobo that used to be configured with 4 x 8 Gig sticks of one manufacturer and identical speed range. When suddenly one of the sticks failed I replaced the faulty stick as well as one good stick with 2 x 16 Gig Corsair Vengeance modules as listed per the buyers guide of this forum. The replacement sticks have the same speed range of my original sticks but are not of the same manufacturer. Total memory installed is consequently 2 x 16 Gig plus 2 x 8 Gig, yielding a total of 48 Gig. When I install this memory so that it should perform in dual channel mode, as per the manufacturers instruction, my rig becomes unstable and reboots out of the blue whilst I am using it. When I then install the memory as per attachment "Working memory layout 1" as reinforced per attachment "Working memory layout 2" I have a stable and usable computing platform. This working memory configuration, depicted in the mentioned attachments is however not consistent with what the manufacturer considers to be dual channel mode, and I certainly would agree, but it works and the rig is stable during operation.

When now moving to Windows and I interrogate my memory status with CPU-Z it says channel "Dual" does it actually mean that the memory is operating in dual channel mode or is it perhaps operating in "flex mode"? Attachment "Windows CPU-Z. Output" refers. What is actually going on ? Kindly assist.

I would really appreciate some expert input on this topic.

Greetings

To have Dual Channel mode operating, the manual recommends to install 2 identical RAM sticks each in the SAME color RAM slots on the motherboard. There are 2 GREY and 2 BLACK slots on the motherboard, and so you should install 2 identical sticks each in a grey slot and then another 2 identical sticks (can be different from the first set) each in a black slot.

You are right, your way of installing the 4 RAM sticks is apparently not the recommended way of Dual Channel mode. But the manual only says that you SHOULD use the same type of RAM sticks in the same color RAM slots, not that you MUST. So apparently even though your way is not the recommended way, it still works in your case.

But still, if this configuration gets you a stable system, and if CPU-Z says "Dual", then the RAM should be in Dual Channel mode and I don't think you have anything to worry about at this point.

 

[Henties]

To have Dual Channel mode operating, the manual recommends to install 2 identical RAM sticks each in the SAME color RAM slots on the motherboard. There are 2 GREY and 2 BLACK slots on the motherboard, and so you should install 2 identical sticks each in a grey slot and then another 2 identical sticks (can be different from the first set) each in a black slot.

You are right, your way of installing the 4 RAM sticks is apparently not the recommended way of Dual Channel mode. But the manual only says that you SHOULD use the same type of RAM sticks in the same color RAM slots, not that you MUST. So apparently even though your way is not the recommended way, it still works in your case.

But still, if this configuration gets you a stable system, and if CPU-Z says "Dual", then the RAM should be in Dual Channel mode and I don't think you have anything to worry about at this point.

Hi @Jamesbond007 thanks for your input. On my GA-Z170X-UD3 mobo all memory slots are one color namely black.
I will leave the memory configuration as is at present and monitor performance and stability for a while before I lose any sleep over this. When I use only 2 identical sticks and insert them in the correct dual channel interleaved manner the rig becomes unstable with frequent out of the blue crashes whilst using the machine. Installing the 2 sticks adjacent to one another returns stability. I begin to believe that there is something wrong with the memory controller or whatever. Nevertheless for now I will leave it at that.
Greetings
Edit:
Memory was repositioned to be consistent with an "interleaved" configuration required for proper "dual channel" functionality.
In addition I manually edited the CAS values so that all memory sticks use the CAS values of the sticks with the highest value, in other words the highest CAS value, thereby downgrading the 2 lower latency (C15) 8 Gig sticks to the higher latency (C16) 16 G sticks.
The bios should actually automatically take care of this but I am not sure whether it actually does.
So far so good Sacrificing the higher achievable latency to make it all work is no big deal for me, as total memory available is advantageous considering what the machine is used for.
@Jamesbond007 might wish to comment on this.
Cheers

 

[Henties]

I consider this thread finalized and will consequently designate it as [Solved]. Setting the memory CAS (latency) values manually as per my post #3 has eliminated the instability due to using 2 types of memory almost identical in all respects except for their CAS values. My Skylake build is now once again stable but this time with 48 gig memory.

Greetings

 

[Jamesbond007]

I consider this thread finalized and will consequently designate it as [Solved]. Setting the memory CAS (latency) values manually as per my post #3 has eliminated the instability due to using 2 types of memory almost identical in all respects except for their CAS values. My Skylake build is now once again stable but this time with 48 gig memory.

Greetings

So your sticks don't have the same latency values, some are C15 and some are C16? That probably explains the instability when all sticks are set to C15. Thanks for your information.

 

[Henties]

Hi @Jamesbond007 Correct it seems to boil down to the lower latency values of the C15 sticks driving the higher latency (slower) C16 sticks. They just cannot keep up and are "outrun" by the slightly faster sticks. Manually applying the highest CAS values, for all sticks in bios, forces all memory sticks to operate at the highest C16 latency values therefore slowing down the 2 x C15 sticks ever so slightly, and yes it seems to work well, so far at least. The "Geekbench" values seem not to have been noticeably affected at all.
Herlock Sholmes at work again
Greetings