For a new laptop that is on order - I haven't got it yet, so I can't
actually look at the existing RAM (I will).
It comes with 4GB in one of the 2 slots. I want to add another 4GB.
Max supported is 8GB.
I already have a stick of Crucial SoDimm here : CT51264BC1339
Crucial's Memory Finder shows as compatible: CT2741253
Both sticks have exactly the same specs : 204 pin, DDR3, PC3-10600,
unbuffered, Non-EEC, 1.5v, CL=9, 512MB x 64.
Is there any difference between these two modules?
If not, why do RAM manufacturers do this?
There probably is a difference between the RAM modules. You've got to
keep in mind that there are hundreds of chip manufacturers. There are
also hundreds of PCB manufacturers. Crucial (for example) has to choose
the PCBs and chips that they use to manufacture RAM boards. These
components are constantly changing from one production run to the next.
The model number of your Crucial RAM board makes sense only to someone
at Crucial. What YOU need to worry about is the specifications of the
RAM board.
Is there a difference between the two modules? Yes. Does it matter to
YOU, the end user? Probably not.
It is likely that both RAM boards would work fine in your notebook.
There is also a slim possibility that one or the other would NOT work.
There is a negligible chance that neither one of the boards would work,
also.
You can't test a RAM board with every laptop ever made...so any
compatibility list that Crucial creates is just a guess.
Similarly, you can't test a motherboard or laptop with every RAM board
ever made. And, you can't guarantee that specs. of the same model
number of RAM board won't change, either. (I've seen it...same model
number, two different competing brands of chips...) So if you see a RAM
compatibility list linked to a motherboard or notebook...it is just a
guess.
The best you can do is match the stated specifications of the notebook
with the STATED specifications of the RAM board, and buy a good name
brand of RAM board. Crucial is great.
But there's no way to 100% guarantee compatibility before you make a
purchase decision. The best you can do is maximize your odds of
success.