I rather run identical modules but if their both identical in speed and voltage Non-ECC u should be ok.
Best was to get an "identical" or matching second module, the original one is 1333 but runs at 667Mhz, so the new one, despite it has faster specs, also runs at the 667MHz speed. I can be mistaken and it's 667 x 2 (1333). About the voltage, if the system runs it, it probably is ok.
This: Obviously you did not get what you wanted or paid for, so you ought to go back to the people you got this pc from and have them correct this if you can
Different Manufacturers Ram will mostly work together, but Matched Ram is always considered the less likely to produce unseen errors. Take it back and complain, it's not what you asked for.
Have you read my post before posting in this topic? Did you saw that I had bought a NEW LAPTOP and that means that all parts have a warranty? Have you thought about that before posting?
Don't get mad at me because you bought a Dell. Return it or keep it. Your choice. It doesn't matter who sold it to you...you got suckered.
What's wrong with Dell? Are you serious? It was mine choice to choose Dell and I will keep it. Please some of the admins to look into this post... is this a normal behavior? It's not just offtopic but also a rude!
My experience tells me that both the RAMs don't need to be exactly same to work. I have used RAMs of different companies bought at different times and they have worked fine. Once I even used 128 Mb RAM (which I actually bought many years later) with 32 Mb RAM and they worked without any problem. It was long time ago. But there have been times they didn't work. As other members have also suggested its better to return the one you didn't order.
@emet I see no problem at all here. And if the information you provided is correct, then you have nothing to complain about the new RAM because the new RAM you bought is better than what you had before. It is only worth remembering that better RAM does not add anything, as it always works under the same conditions, what are dictated by the worst component. Thus, the new one will work exactly under the conditions that the RAM that was originally there. (Each chain is just as strong as its weakest link. - Old folk wisdom).