Max Ram Macbook Pro?

Douge

macrumors newbie
Original poster
Jul 21, 2007
16
0
Princeton
I am curious as to what enables the new Macbook Pro to support 4 gb versus the 2 gb of the old Macbook Pro.

I clearly don't know very much about Ram and I don't yet need 4 gb but I want to understand why there is a physical limitation. The Mac Pro is said to hold a max of 16 gb of RAM on apple's site but it can actually hold 32 gb. How is this technology different? Are there ways to upgrade an older Macbook Pro to hold and use 4gb? Thanks for you help!
 

squeeks

macrumors 68040
Jun 19, 2007
3,389
14
Florida
I am curious as to what enables the new Macbook Pro to support 4 gb versus the 2 gb of the old Macbook Pro.

I clearly don't know very much about Ram and I don't yet need 4 gb but I want to understand why there is a physical limitation. The Mac Pro is said to hold a max of 16 gb of RAM on apple's site but it can actually hold 32 gb. How is this technology different? Are there ways to upgrade an older Macbook Pro to hold and use 4gb? Thanks for you help!
no the max can not be physically changed without replacing the logic board, the limit is in the memory controller and how the cpu accesses the memory, there has always, and will always be a limit in how much memory apps and hardware can handle. its technical.
 

Zel

macrumors regular
Jul 7, 2007
172
0
There's only so many digits avaliable in the system for addressing memory.

If you want to have the CPU talk to 9999 different bits of memory, (if it used decimal) then you would need four places wide.

2GB is 16gigabits which is 16,000,000,000 bits and if it used decimal, that would need eleven digits to address each peice independently, get it?

It uses binary instead of decimal, so it takes more than eleven, but that doesnt matter, the thing is, old ones can only address 2GB and the new one can do 4GB (intel rumors 8 tho...)

anyway, you cant change it or 'fix it' sorry.
 

CalBoy

macrumors 604
May 21, 2007
7,829
36
I am curious as to what enables the new Macbook Pro to support 4 gb versus the 2 gb of the old Macbook Pro.

I clearly don't know very much about Ram and I don't yet need 4 gb but I want to understand why there is a physical limitation. The Mac Pro is said to hold a max of 16 gb of RAM on apple's site but it can actually hold 32 gb. How is this technology different? Are there ways to upgrade an older Macbook Pro to hold and use 4gb? Thanks for you help!
Both of the other posters have given you good answers, so I'll just put the cherry on top. If you really don't do anything that needs a lot of RAM, then don't worry about it now. RAM is always becoming cheaper. If you're looking into a mbp now, then buy it and upgrade your RAM a year or two from now when you feel it's getting slow. Don't worry about being left behind, 4 GB will get you pretty far;)
 

ab2650

macrumors 6502a
Jun 21, 2007
714
0
Both of the other posters have given you good answers, so I'll just put the cherry on top. If you really don't do anything that needs a lot of RAM, then don't worry about it now. RAM is always becoming cheaper. If you're looking into a mbp now, then buy it and upgrade your RAM a year or two from now when you feel it's getting slow. Don't worry about being left behind, 4 GB will get you pretty far;)
I agree; the longer you wait the better. When you need it, get it.
However, i think the OP was either looking at or owned an older revision of the MBP. Keep in mind the original CoreDuos were 2GB max, where the Core2Duos (the revision before last) were 3GB max, and only the latest "Santa Rosa" MBPs are 4GB max.

But to answer the question: No, those are the true limits of the machine; If you put more than specified, it will not address properly (anyone care to test? :p)
 

devman

macrumors 65816
Apr 19, 2004
1,240
4
AU
no need to test anything. If it's a NAPA chipset then the memory controller is 32bit.
 

matticus008

macrumors 68040
Jan 16, 2005
3,341
0
Bay Area, CA
The new chipset includes improvements in memory addressing. Despite the theoretical limits of RAM capacity, most consumer products have lower limits imposed by other constraints (usually cost). Keep in mind that unless the rest of the computer can access the memory and keep up with the amount of data flowing in and out, there's no point in increasing the capacity.

There is no way of upgrading an older product, short of swapping out the logic board. If you could get a chipset to recognize a higher memory limit, it would do no good, since the rest of the system was not designed to handle it.

Edit: strange, when I replied none of these other replies were showing up. How odd!