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Can I run these 2 RAM modules together?


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Hi, I have a MSI K7N-420 Pro (nforce 1st generation) board. Latest BIOS, Windows 2000-Professional.


I originally built it with 1 512MB Corsair RAM module about 2 years ago.

That part # is: CM64SD512-2400C2H It has the standard Black XMS heat spreader on it as most Corsair modules do today. It is a 2400 (300MHz) speed module.


I recently decided to upgrade and add another 512MB module 3 months ago. However I could no longer find the original Corsair part #'s any more for 2400 & ended up buying a 2700(333MHz) Corsair module instead. I figured it would be backwards compatible since I would be running it at only 266MHz speeds. Both modules are rated to perform above 266MHz @ either 300MHz or 333MHz. Underclocking should cause less problems. Well, there were no problems for a little while but now if both modules are installed I get random BSOD and program errors. This only happens if I run the system with both modules in the computer. If I run on only the 2400 or 2700 RAM module nothing ever goes wrong. Put them together & it's a cluster fu*k of random BSOD. I have plenty of power for the computer. Antec 400W running pc with not alot of hardware. I used memtestx86 to test each module separately & they both passed. I tested them together & the both passed. I tested the modules with Checkit & they both passed. But once again the system will only run stable with either one or the other RAM module installed not both at the same time. The most common BSOD was for Kmode_exception_not_handled or IRQ_not _less_equal. But varies. All drivers are up to date. No hardware conflicts. Computer has run solid for 2 years until upgrade & continues to run solid wiht only 1 module in the system.


I have been troubleshooting this issue with Microsoft for the past month and I am coming to the only conclusion that it may be a compatibility with the RAM modules. Microsoft finds nothing wrong with the computer & considers it squeaky clean. It runs exmplary with 1 RAM stick as it did before I upgraded 3 months ago.


I run both modules @ CAS 2, 266DDR (133x2) with no overclocking. I have tried CAS 2.5 but same crashing results with both RAM installed.


Original RAM Module: CM64SD512-2400C2H in Slot 1

New RAM Module: CMX512-2700C2 in Slot 2

Slot 3 on board is empty


Both RAM modules look identical just different rated speeds. I run both modules at equal or less their rated speeds.


So what do you think? Incompatible? Something else?

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Most likely, you will not be able to use these 2 modules together. They use different ICs and are different enough that apparently your MOBO cannot cope with these differences. If your system will run the PC2700 module, you may need to part with the PC2400 module and find another PC2700 module.



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That's what I was thinking. Anyone else agree with this before I act? I can definitely get another 2700C2 identical module if needed. I'll just sell the 2400 module.


The computer did run fine for a few weeks with both modules installed when I first added the 2700C2 module but has been steady on crashes now if I try both together even though they both pass separate or combined memory tests.

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