03-19-2013 08:25 PM
I understand well that the CT# on the actual memory module received is different from the CT# given by the selection tool (or system scanner), but it seems that Crucial would have a lot fewer Forum questions to answer (and happier users) if there were a cross-reference available on the website.
For example, I acquired a well-used Toshiba Tecra M7-7331, and simultaneously checked to see if some of the Crucial modules I already had would work in it. The selection tool told me that the correct 2GB module for this machine is CT2751520 (CT2751523 for the 2x2GB kit).
Well, the published specs for that module exactly match the CT25664AC667.8FC2 modules that I already have in abundance, and I could see from the Forum that this module is the internal number Crucial ships for a *lot* of external CT#s.
However, none of the CT25664AC667 modules will run in the PC; they were known good at last use, I did all possible permutations of module and position, and the PC runs fine with its original 512MB modules,
Can someone confirm that, indeed, CT25664AC667 modules are incompatible with this PC, and if so, why the published specs don't reflect the incompatibility?
Solved! Go to Solution.
03-20-2013 02:40 AM
I'm sorry to hear that you are having problems with your memory upgrade.
I have had a look at this system and I can't locate a M7-7331 but I can locate a M7-S7331, is that your system?
If so then CT25664AC667 is the correct memory type for that system. You said that you have been trying the memory next to your existing 512MB module is that correct? If so can you try the 2GB module on it's own in the system?
It could be a compatibility issue between the two different memory types and that's why it's not working. Also can you confirm the full part number on the memory module, for example CT25664AC667.16FE
Once we have that information we can look in to it further for you.
03-20-2013 09:54 AM
Thanks for the quick reply, CJ!
Oops! Yep, I left off the "S" in the model number. M7-S7331 is the system model number, but I also have a M7-S7311 on the way that I hope to upgrade similarly, so please include it in your reply.
My original post included the full module code, CT25664AC667.8FC2.
I did not try to mix the original 512MB modules with these 2GB modules. I installed the 2GB modules in all permutations (and I'm confident I seated them correctly each time):
I do get differing Power LED flash codes at power-up, but I have been unable to find any reference online for looking them up. I can find lots of help with the DC Power LED flash codes, but those don't help.
You didn't ask about the BIOS, but I have the latest version of that, too – 3.50.
03-27-2013 10:29 AM
Thanks for your reply and the information you have provided. I'm sorry I never noticed the full part number in your original message, that's a mistake on my part and I'm sorry about that.
I have had a look at this system and I think I know what the problem is with this memory. The memory you have has 8 chips on it and is what's known as high density memory. However the most common type of DDR2 2GB modules have 16 chips and are known as low density memory.
Some systems can only support either high or low density memory and it sounds like your system does not like memory with 8 chips in total.
What you will need to do is order the correct memory for your system which will be the 16 chip version. I'm sorry for any problems caused but it's actually a system limitation and not the memory itself.