Buying Matching RAM for Dual Channel Memory

[azkm]

Hi, I've got a new laptop (Acer Aspire 5740 with Core i5 430M running 64-bit Windows 7)

It has 3GB of memory, and I'd like to increase it. I've been reading about matching the memory modules, but I'm still a little unclear about it.

I've downloaded CPU Z and run it. The memory tab is blank except for size (3072MBytes), but the SPD tab seem to have information about the installed memory.
There are two slots on the laptop, one has 1024MB and the other has 2048MB. So they are not matched at the moment?

I was thinking of replacing the 1024MB module with a second 2048MB module, to get 4GB of dual channel memory.

(I hope you can set me right about any point in this post that is wrong and confused - I'm not a computer whizz.)

The modules in the laptop are Samsung DDR3 PC3-8500F (533Mhz).

In order to get a module that's matched to the current 2GB module, do I need to buy the exact product (from Samsung) or will any 2GB module that's DDR3 and 533Mhz do the trick? What exactly must be matched?

I ask because I can't seem to find that exact module for sale. The part number, M471B5673EH1-CF8, seems to point to a module that runs at 1066Mhz. Should I buy that?

I ran the Crucial system scanner, and apart from telling me I need 8GB of memory, it seemed to suggest that I need to replace both modules to get matching pairs. I take this to mean that a Crucial module can't be matched with a Samsung module. The scan results page is here:

http://www.crucial.com/systemscanner/viewscanbyid.aspx?id=33F209A531D926C3#

Am I going to have to replace both modules to get a matched pair?

I'd be very grateful for any help or advice.

 

[GhislainG]

The part number, M471B5673EH1-CF8, seems to point to a module that runs at 1066Mhz. Should I buy that?

CPU-Z shows the clock speed (533MHz); DDR runs at twice the clock speed, i.e., 1066MHz. You should order the exact same module. Other modules may work, but system stability might not be as good.

 

[azkm]

Thanks so much for such a quick response and for finding the error in my confused post.

Now I have another question: Given that Samsung is a well-known brand, is there a danger of buying a counterfeit product over the internet? Amazon has the module for 78 quid, and there are a few marketplace sellers offering it for fifty (stating "OEM", "comes in a different box", etc.) Are they likely to be dodgy?

 

[GhislainG]

The risks are relatively low, but you need to make sure that they sell the same part number and not some equivalent based on different memory chips.

According to http://eshop.macsales.com/item/Samsung/8566DSM3S2GB/, those modules are used in several MacBook. There are several used modules on Amazon that were pulled from a MacBook: http://www.amazon.com/gp/offer-listing/B001LGBU4C/ref=dp_olp_used?ie=UTF8&condition=used

 

[azkm]

So is it a good idea to buy used memory? And is that first link for a new module or a used one? It doesn't seem to say.

 

[GhislainG]

The Amazon link is for used modules (see the condition column), but I consider the risks as low and you know that they most likely work fine.

 

[azkm]

Sorry to keep buggin you, but is this the right module:

http://www.amazon.com/gp/product/B002BJ37JO/sr=1-10/qid=1277659146/ref=olp_product_details?ie=UTF8&me=&qid=1277659146&sr=1-10&seller=

 

[GhislainG]

I can't see the picture and no part number is provided. Not all MacBook use the M471B5673EH1-CF8 modules and the asking price is very low. It's up to you, but I'd first contact the seller to ask what the part number is and I certainly wouldn't mention that I'm after a Samsung M471B5673EH1-CF8 module.