RAM of different capacities ?


I have a quicky for you guys...

My boss has a Lenovo W520 with 2 x 4 GB of RAM, DDR3.

He wants to upgrade, I was suggesting buying 2 x 8GB, as the W520 offers 4 slots.

He challenges me about the fact that they aren't the same capacity. I was almost sure it wasn't a problem, since they were paired with another stick of same capacity/size/speed...

But he insists that I check this out. Now I have a doubt...
I tried to google it, but can't seem to find a way to have google spit it out...

Anyone knows about this ?
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Gary CaseConnect With a Mentor RetiredCommented:
It's not an issue at all.   If you add 2 8GB modules, he'll have 24GB of RAM.

If you install them incorrectly, then you won't get the optimal synchronous dual channel mode -- but it's almost certain the original RAM is already installed in one pair of slots;  so all you have to do is populate the remaining two slots with the 8GB modules and everything will be fine.
It depends on what the hardware will support. There is usually a memory configuration matrix on the manufacturer's website or in the documentation that tells you what you can and can't do.
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Gary CaseRetiredCommented:
... if it'll make your boss feel better, download CPU-Z, click on the Memory tab, and confirm the current operating mode [Most likely shows Dual channel in Symmetric mode].

Then install 2 additional 8GB modules and repeat the process.

There IS one thing you should check before buying the additional modules:   the rated speed of the current modules.    Be sure you buy modules that are the same (or higher) speed ... otherwise the operating speed of the memory may be reduced (depending on whether it's currently operating at the max speed of the installed modules -- CPU-Z will show you this on the Memory tab).
He's got a 64 bit OS,right?
Gary CaseRetiredCommented:
"... He's got a 64 bit OS,right? ..."  ==>  Considering he already has 8GB of RAM (and wants more) I'd say that's reasonably apparent :-)
I've seen systems with 32 bit preinstalled and 8 gb ram upsold as a come on.

Marketing people sometimes lack a sense of morality.

Remember the Vista compatible hardware fiasco?
maxalarieAuthor Commented:
Thanks for your answers.
Yes, it is on a 64 bits OS :)

I will try that Garycase, thanks a lot !
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