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Old 08-11-2007, 06:20 AM   #1
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MB Maximum RAM Capacity Question

I was looking at some Asus MBs the other day and noticed that they all have a max of 4GB of RAM that they can hold.

Is that a limit imposed by Windows or inherent in the 32-bit or 64-bit architecture?

I ask because with the dual-core and now quad-core cpu's, I have to wonder how much use they'll be if they're all fighting over the same limited pool of RAM?

Thanks for any info you can provide.
Old 08-11-2007, 07:31 AM   #2
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It is a limitation of the 32 bit architecture. If you want to use more memory, and you have a 64 bit chip, you can install a 64 bit distro. Some distro's like SuSE are biarch, and allow you to install 32 bit programs. SuSE will install the 32 bit version of Firefox for example, so that it is easier to find plugins.

You will also want to read the docs for the motherboard to see if there are any other ram limits imposed.
Old 08-11-2007, 07:36 AM   #3
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4GB is simply the maximum that some motherboards will accept; but most recent ones will support at least 8GB.
Old 08-11-2007, 07:43 AM   #4
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Properly built (32-bit) motherboards with PAE should be able to support 64 Gig of RAM.

Linux can use this memory - even though each (32-bit) process is limited to 4 Gig (virtual) address range.
If the mobo has an inherent limit, go get a better one - generally that means spend more.
Old 08-11-2007, 09:57 AM   #5
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My new M/B (ASUS P5B WiFi Deluxe) supports 4 GB on board (4 slots), but I read in the book that win 2000 and XP can't see more that 3 GB. To use all 4 GB we must use the 64-bit versions of those systems, like server editions etc. Of course, there is nothing else than m$ for them. The world's limits are the m$ doors.

I wonder what a Linux system would detect with 4GB. My system is intel E6600, so I couldn't use the -64 versions made for AMD 64 architecture. Anyway, I have just 2GB on board.

Some new M/Bs support up to 16GB on board.
Old 08-11-2007, 10:16 AM   #6
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Thanks so much, everyone for the very helpful information. I'm running CentOS 5.0 64-bit with an AMD-64 3800+ dual core.

What is PAE amd I'll check the manual?

Thanks again for the information.
Old 08-11-2007, 10:18 AM   #7
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I'll answer that one for you, masterclassic; my experiences with an ASUS P5B motherboard are:

with memory mapping enabled:
Ubuntu 32 detects 2GB
Fedora 64 bit detects 4GB
Debian 64 bit refuses to boot until I tell it that I have 6GB of RAM installed
XP 64 sees 4GB
Solaris 64 bit sees 4GB

without memory mapping:
they all see 3GB

Last edited by jay73; 08-11-2007 at 10:21 AM.
Old 08-11-2007, 10:23 AM   #8
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You don't need PAE. That's for 32 bit operating systems.



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