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Discussion Starter #1
Bare with me on the details, but here we go. I have a P9X79 Motherboard running 8x2gb sticks of Ddr3. I have two banks (left and right) with 4 sticks each bank. The left bank is made up of 3 1600mhz-rated, 1.65v Corsair XMS3 (TR3X6G1600C9) and a single stick of 1333mhz-rated, 1.5v Corsair (TR3X6G1333C9). The right bank is made up of 4 sticks of the same model 1333mhz as shown above. For the most part, this combination has worked well without changing any settings. System specs:

3930K @4.4ghz (Multi+Voltage changed only)
P9X79 Mobo
Gtx 980
Ssd+2hdd
16gb Corsair
600w Evga psu
Corsair h110i gtx cooler

Recently however (likely a result of my recent endeavors in trying overclocking), I have been getting issues with booting the system intermittently (in Windows however, rock-stable). It will boot loop, until I either A. Reset, or B. Gives me an "Overclocking Failed, Press F1" message. When it gives me the Overclocking failed message, it will show me either 16gb of ram, as I should have, or 12gb of ram. When it shows 16gb, I can simply press escape, and it will boot to Windows with no issues. When it gives me 12gb, upon checking the Spd info in the bios, the bios will see all sticks. However, it will show me two channels in the left bank (refer to earlier in post) are "Abnormal". I will provide an image for reference below. I have tried setting the left channel to 1.65v, which appeared to work at first, but I eventually noticed did not entirely rid myself of the intermittent memory error. Again, when in Windows, I have no blue screens or crashes of any sort.

If anyone has any suggestions, questions, or ideas, I would love to hear them! Thanks!

-Thanacae

 

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As you are finding out, mixing memory can be problematic, Sometimes it works, sometimes changing settings manually can get it to work, and sometimes it just doesn't work.

Background (simplified):

When any computer starts up the BIOS reads the SPD tables programmed into the memory stick that is closest to the CPU (ie. the memory controller). You can download and run CPU-Z to see the SPD tables in your memory. The BIOS then uses the memory speed and memory timings from the SPD tables that corresponds to the CPU speed that is set in the BIOS. It uses the SPD table from that one stick and applies all the settings from it to all the sticks.

Try putting the stick with the slowest speed and the loosest timings into the first slot. If that doesn't work then it's time to start manually setting things in the BIOS.

Stay away from XMP profiles. They are a joke! The whole concept of XMP is faulted because the person writing the XMP SPD table for the memory has no idea what motherboard, CPU, what other peripherals are connected to your motherboard, nor even how many memory sticks you have installed. So, XMP profiles are just a guess at what memory overclock will work for the widest range of motherboards, CPUs, memory, and computer configurations. They have nothing to do with what your specific setup is. ... they're just a guess.
 

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Discussion Starter #3
Quote:
Originally Posted by billbartuska View Post

As you are finding out, mixing memory can be problematic, Sometimes it works, sometimes changing settings manually can get it to work, and sometimes it just doesn't work.

Background (simplified):

When any computer starts up the BIOS reads the SPD tables programmed into the memory stick that is closest to the CPU (ie. the memory controller). You can download and run CPU-Z to see the SPD tables in your memory. The BIOS then uses the memory speed and memory timings from the SPD tables that corresponds to the CPU speed that is set in the BIOS. It uses the SPD table from that one stick and applies all the settings from it to all the sticks.

Try putting the stick with the slowest speed and the loosest timings into the first slot. If that doesn't work then it's time to start manually setting things in the BIOS.

Stay away from XMP profiles. They are a joke! The whole concept of XMP is faulted because the person writing the XMP SPD table for the memory has no idea what motherboard, CPU, what other peripherals are connected to your motherboard, nor even how many memory sticks you have installed. So, XMP profiles are just a guess at what memory overclock will work for the widest range of motherboards, CPUs, memory, and computer configurations. They have nothing to do with what your specific setup is. ... they're just a guess.
I agree that mixing ram can be problematic, but during the purchasing stage of the build
I THOUGHT that all 8 were matching, until I recieved them. They still worked together well though, up until now. I set the timings manually (all 8 have same timing specs actually), with the only other change being the voltages of the two sets of banks (left & right). I appreciate your response!
Sidenote: I did attempt Xmp earlier in the oc process, and I did actually run with all sticks at 1600,but It appeared I maybe wasnt stable, so I subsequetly disabled xmp.
 

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Quote:
Originally Posted by Thanacae View Post

I THOUGHT that all 8 were matching, until I recieved them. They still worked together well though, up until now. I set the timings manually (all 8 have same timing specs actually),
There are over 20 SPD timings, most of which you can't even see without specialized software.

I could go into a lot of the reasons why even though the advertised timings are the same they really aren't. That;s why you should always buy all the memory you're going to have installed all at once, from one vendor, as a "matched set".
 

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Discussion Starter #5
Quote:
Originally Posted by billbartuska View Post

There are over 20 SPD timings, most of which you can/t even see without specialized software.

I could go into a lot of the reasons why even though the advertised timings are the same they really aren't. That;s why you should always buy all the memory you're going to have installed all at once, from one vendor, as a "matched set".
At the time, my 3 main concerns were A. They all look sexy (which they do), B. Quad channel, and C. 16gb sticks that are the same. I wasnt aware of timings and such when I purchased a year ago. All i knew was that it would be okay to use 1333 and 1600 together, because it should downclock the 1600 to match. On all 8, the primary timings on the sticks match up. Im now aware there are many other timings (my bios has a ridiculous amount of Dram timing control), but I do not understand how to properly set them up. I have them all set to "Normal". All 8 sticks are XMS3 series if that helps, with the only percievable difference I can tell is the Mhz speed. The models are included in OP if that may help.
 

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Try setting the main timings to something simple, like 10-10-10-28 2t and set 1.65vdimm. See if this works, going off the 1600, it should be rated at 9-9-9-24 with 1.65v, where the 1333 has the same rated timings at 1.5v. Raising the voltage to 1.65v may give it the ability to run the same timings at 1600.... but we dont know the ICs involved nor their binning, so it could also take more voltage, or need looser timings to hit the speeds that you are looking for.

I wouldnt run memory on auto timings, especially when mixing modules. They may have the same heatspreaders, but sometimes different chips. On some systems you can get them working, but you are limited to the worse timing in each slot and applying it for all of the sticks. If 7 of the sticks can run 7-8-7-24, but one can only run 9-9-9-28... then you are stuck running 9-9-9-28 on all of them.

I havent messed around much with x79 with mixmatching modules... but I think more or less its the same experience when setting timings.

I have yet to have any DDR3 memory that I couldnt run 1800mhz with, its just finding out if you can get these different memory modules to play nice with each other. Look at their SPD profiles, see where they differ.

Once you get a stable baseline, then you can tighten the timings a little and see when it gets unstable... or loosen the timings more and try to get more frequency.
You can start with 11-12-12-32 2t at 1.65v and try to see what the maximum memory speed that you can post is, then you know where you can start working to maximize performance. In general, frequency is more important than timings on x79, but you want as good timings as you can run stable.

I will typically compare a series of benchmarks with the tightest stable timings from 1600 up to the maximum speed achievable. Often the setting just under the maximum speed you can hit is the fastest performing divider.
 

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Quote:
Originally Posted by EMUracing View Post

Try setting the main timings to something simple, like 10-10-10-28 2t and set 1.65vdimm. See if this works, going off the 1600, it should be rated at 9-9-9-24 with 1.65v, where the 1333 has the same rated timings at 1.5v. Raising the voltage to 1.65v may give it the ability to run the same timings at 1600.... but we dont know the ICs involved nor their binning, so it could also take more voltage, or need looser timings to hit the speeds that you are looking for.

I wouldnt run memory on auto timings, especially when mixing modules. They may have the same heatspreaders, but sometimes different chips. On some systems you can get them working, but you are limited to the worse timing in each slot and applying it for all of the sticks. If 7 of the sticks can run 7-8-7-24, but one can only run 9-9-9-28... then you are stuck running 9-9-9-28 on all of them.

I havent messed around much with x79 with mixmatching modules... but I think more or less its the same experience when setting timings.

I have yet to have any DDR3 memory that I couldnt run 1800mhz with, its just finding out if you can get these different memory modules to play nice with each other. Look at their SPD profiles, see where they differ.

Once you get a stable baseline, then you can tighten the timings a little and see when it gets unstable... or loosen the timings more and try to get more frequency.
You can start with 11-12-12-32 2t at 1.65v and try to see what the maximum memory speed that you can post is, then you know where you can start working to maximize performance. In general, frequency is more important than timings on x79, but you want as good timings as you can run stable.

I will typically compare a series of benchmarks with the tightest stable timings from 1600 up to the maximum speed achievable. Often the setting just under the maximum speed you can hit is the fastest performing divider.
That is some awesome info, I appreciate it! For now, my goal is to attempt to get all 8 to reliably post 100% of the time, as my only issue at the moment is getting it to post every other time, as currently it is hit or miss. I shall start playing with the timings today, thanks again!
 

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Also try playing with the slots that the different speed sticks are in on the same channel (so channel B, switch B1 with B2).

If you still get the error, switch one stick from B to C or D. See if you still get the error and on which channel. It could be that the motherboard is sensitive to differing spd modules in the same channel.
 

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Discussion Starter #10
I have tried swapping them, matching them to the proper channels, and simply randomizing them multiple times. Whenever it fails, the same 2 slots every time return the error. I would have pinned that to bad ram slots, but as I said, the issue is intermittent. Has me very confused.
 

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Thought Id report back. I was about to call it quits and consider the two slots dead, but I read somewhere a cpu reseat may help. So I completed the reseat, and now all channels are working properly! I have even dialed in a 1600mhz on the ram, and it appears they took it properly. I suppose now the plan is to perhaps push the ram further, but I am much happier that I am getting 16gb of ram reliably.
 
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