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CMX5123200C2 and CMC2GX1M2A400C3 coexistence.


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Hi all, this is my first post so I apologize if I'm making some mistakes.

I've searched thru the Forum, so I suppose I've already some answers but I'd like to have confirmations and some new info.


I've decided to upgrade memory on my old system adding two 1 Gb DIMMs of CMC2GX1M2A400C3.

Since I'm not an overcloker or a speed fanatic, I've taken into consideration adding 2 Gb of VS1GB400C3 Value Select RAM but I'd like to stay with CAS Latency 2 (as now is), moreover I suppose that CMX5123200C2 and CMC2GX1M2A400C3 are more likely compatible.


I've checked it with Corsair compatibility tool, so I'm sure that motherboard compatibility with CMC2GX1M2A400C3 is not an issue (http://www.corsair.com/configurator/product_results.aspx?id=2240).


My doubts are:

1) could presently installed CMX5123200C2 (mobo sockets 1 and 2) coexist with new CMC2GX1M2A400C3 (mobo sockets 3 and 4)?

2) if coexistence is possible, would it be better to put CMC2GX1M2A400C3 to sockets 1 and 2 and move CMX5123200C2 to sockets 3 and 4? Is there any difference in performance and/or stability?

3) DDR voltage has always been set (by motherboard default) at 2.55v and my sistem is rock stable since day one. CMC2GX1M2A400C3 specs says 2.75v. Had I to increase DDR voltage to match CMC2GX1M2A400C3 specs or could I keep 2.55v?



Many thanks.

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  • Corsair Employees
Mixing and matching kits is not always the best idea and we cannot gurantee the memory will run together. You would most likely run into issues where you would need to slow the memory down to 333MHz and loosen the case latency to 3-3-3-8 and set the memory voltage to 2.75V
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On configurator tool CMC2GX1M2A400C3 is listed at 2-3-3-6-2T and that's the reason I looked at that RAM type.

But then I found a CMC2GX1M2A400C3 PDF spec sheet saying 3-3-3-8, so I suppose configurator has a typo.


Too bad, since I'd like to keep CASL 2 to keep performance at current level and I can't find in stock other Corsair DDR1 with that latency (not even TWINX2048-3200C2PT).

It seems to me there is no available 1Gb DIMM true successor to CMX5123200C2.

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  • 1 month later...

Just an update, for anyone interested.


I realized I *really* needed more memory, even at the expense of speed (I was worried just by increased CASL, memory clock has ever been set to 333 Mhz).

So I ordered two 1 GB DIMMs of CMC2GX1M2A400C3 and one week ago I added them on my computer, still worried for possible system stability issues.


At first I didn't changed anything on BIOS and (as expected ...) Windows didn't boot (blue screen).

Then I just changed BIOS letting it to choose parameters (DRAM timing selectable "by SPD") and disabling "Enhance DRAM performance".

I kept DDR voltage at 2.55v.


After that ... all was perfect!

System upgraded from 1 GB to 3 GB, with no issue at all. :):


Not only: I tested RAM performance with Everest tool, before and after the upgrade, and I found no significant difference.

System is absolutely stable since upgrade (and, of course, much less prone to Windows swapping ...).

I also ran a full memory test with MemTest-86 v.3.5 and it was passed.


I suppose that the good quality of this old board, of all the DIMMs (of the same manufacturer) and the fact my system is not (and hasn't ever been) a "souped up" or overclocked system has something to do with the happy coexistence of my mixed RAM banks.


Anyway ... happy 3 GB (mixed) Corsair RAM owner here! ;):

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