
64-bit MacBook Pro notebooks may take up to 16GB of RAM - davethenerd
http://www.powerpage.org/2011/10/26/64-bit-macbook-pro-notebooks-may-take-up-to-16gb-of-ram/
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kogir
This has only ever been a chipset limitation. Not that long ago there were
64-bit capable Nvidia chipsets that could still only address 3GB of physical
RAM due the way they mapped device memory into the system address space [1].

Sandy Bridge processors contain their own memory controllers that can address
16GB-32GB of RAM. True for any system they're in, as long as all channels are
linked to physical DIMM slots [2].

[1]
[http://blogs.msdn.com/b/hiltonl/archive/2007/04/13/the-3gb-n...](http://blogs.msdn.com/b/hiltonl/archive/2007/04/13/the-3gb-
not-4gb-ram-problem.aspx) [2] <http://ark.intel.com/>

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pasbesoin
Hmm, your links imply that my old Inspiron 6400 might be able to take two 2 GB
modules (the manual says it can handle a 2 GB module) and have access to
something more than 2GB of addressable RAM. Anyone happen to try this with
this or a similar model Dell? (The 6400 is equivalent to the 1505, IIRC. Its
manual says it's limited to 2 GB of RAM.)

EDIT: Answering myself, it appears it can take 2 x 2 GB sticks. The following
Dell forums thread describes this, although this particular post linked claims
that the configuration will disable dual channel memory access (but then
again, other posters are happy and view the expansion as an improvement).

[http://en.community.dell.com/support-
forums/laptop/f/3518/p/...](http://en.community.dell.com/support-
forums/laptop/f/3518/p/18322272/18445258.aspx#19007577)

EDIT2: I've seen some other comments that dual channel remains enabled (with
matched 2 x 2GB sticks). I guess I'll give it a go.

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hemancuso
Well known. Here are kits for MacBook Pros:

[http://eshop.macsales.com/shop/memory/Apple_MacBook_MacBook_...](http://eshop.macsales.com/shop/memory/Apple_MacBook_MacBook_Pro/Upgrade/DDR3_1333MHz_SDRAM)

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lancefisher
I recently found out that I could upgrade my late 2008 MacBook Pro to 8GB of
RAM. The specs say only 4GB will work, but soon as I found out that 8GB should
work I upgraded for just $50.

You need an EFI firmware update that you may have already installed. Read
more: [http://www.macrumors.com/2011/03/07/secret-firmware-
update-u...](http://www.macrumors.com/2011/03/07/secret-firmware-update-
unlocks-support-for-8-gb-ram-on-late-2008-notebooks/)

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gojomo
If I understand correctly, more RAM draws more power.

Anyone have an idea of the hit to battery life caused by going to 16GB?

~~~
dqminh
no, more ram means less power consumption because you are accessing hard drive
less often.

~~~
cylinder714
For what it's worth, the OpenBSD team is working on improved buffering for
high-RAM machines:

"Computers today have immense quantity of unused memory. This new software
almost works, we still have some minor bugs to fix, but the results so far are
incredible. On computers with 16GB of RAM we can dedicate as much as 13 GB to
buffering and almost no data is read from the hard drive, everything is in the
RAM. It performs even faster than SSDs. We only have to write to the disk
anymore and that’s mainly for reliability reasons. I estimate we’re a year
away from the whole thing working flawlessly. From this aspect the 6 month
release cycle is a bit limiting."

[http://undeadly.org/cgi?action=article&sid=2011101806163...](http://undeadly.org/cgi?action=article&sid=20111018061633)

~~~
gonzo
seriously, you think OpenBSD invented the buffer cache?

