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Asus P7P55D Pro and CMX4GX3M2A1600C8 4 out of 8gb


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I have searched all day regarding my problem, but found no real solution.


I am trying to run 4x2gb of CMX4GX3M2A1600C8 on a Asus P7P55D Pro motherboard, but they only show up as 4gb instead of all 8gb.

In the manual for the motherboard, it states:


"Due to intel spec definition, X.M.P. DIMMs and DDR3-1600 are supported for one DIMM per channel only."


When the motherboard runs on auto-settings, it tries to run them on 1333mhz and 9-9-9-24.

In BIOS, I have tried to manually choose X.M.P profile in the "AI Overlock Tuner", and then it find the profile #1 with the right settings, 1600mhz 8-8-8-24 1.65v, but still only 4gb of usable memory.

Same with D.O.C.P profile and choosing DDR3-1600, runs with right latancy and all, but still 4gb.

I have even tried to manually set them to a lower speed, but still - no good. (Unless I missed a vital setting, aint to experienced.)

I have tried swapping the DIMM-modules around 3 times, to make sure that they are connected like they should, and so that possition wasnt a problem.

I have tried all the DIMM-modules one by one, and they work just fine then, all show up in BIOS as 2gb.

I then flashed BIOS successfully to v.0711, but still same problem with all the settings.

I also tried turning on/off Memory Remap, but nope..


The memory modules are listed as supported on corsairs Memory Configurator, but maybe thats only on 2 DIMMs?


Is there really a big difference on the CMX4GX3M2A1600C8 and CMD8GX3M4A1600C8 thats on the supported list? Big enough to make the CMD8 work on 4x2 DIMMs while the CMX4 cant on 4x2 DIMMs?

Shouldnt it, on paper, have the same issues since they are 4xDIMMs X.M.P. and 1600mhz?



Is there a manual memory setting to bypass this issue, like downclocking/overlocking the memory to get around the restrictions?

Any other known settings that works?

Or am I screwed and need to get my hands on other slower memory-modules to get below the 1600-restriction?


I dont have any OS installed right now on the drive.


Thanks in advance

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  • 4 months later...
  • Corsair Employees
Yes there is a difference between running 2 of the 4GB kits and one of the 8GB kits. You can try manually setting the timings to 9-9-9-24 and the memory voltage to 1.65v then try setting 1600MHz but if that doesn't work you would need to slow the memory frequency down to 1333MHz.
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