Physical Address Extensions: explain

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~El~Jefe~
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Physical Address Extensions: explain

Post by ~El~Jefe~ » Sun Aug 15, 2010 10:07 am

Physical Address Extensions

explain that crap eh?

I was looking at a D510 and noticed it had ability to use 64 bit OS's but then it said it has Physical Address Extensions = 32 bit.

anyone know if this is hobbled or just the way modern home cpu's work as they arent 64 bit only?

Matthew
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Post by Matthew » Mon Aug 16, 2010 9:32 am

The D510 is an x86-64 processor. It can run 64 bit and 32 bit operating systems. It's the same instruction set as the core 2, i7, and everything in between. It's as real as any other '64 bit' processor you'd buy today.

Physical address extension (PAE) means that the processor will also allow a 32 bit operating system to access more than 4GB of ram, if the OS supports PAE.

All of this only matters if you have a machine with 4GB or more of ram, and want to install a 32 bit OS for some reason. Like maybe you already own a copy of XP 32 bit, or you use linux, and things break when you use the 64 bit version. I have an Atom 330 with 4GB or ram, and use 32 bit OSs.

I hope that clears things up.

colm
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Post by colm » Mon Aug 16, 2010 10:46 am

Matthew wrote:The D510 is an x86-64 processor. It can run 64 bit and 32 bit operating systems. It's the same instruction set as the core 2, i7, and everything in between. It's as real as any other '64 bit' processor you'd buy today.

Physical address extension (PAE) means that the processor will also allow a 32 bit operating system to access more than 4GB of ram, if the OS supports PAE.

All of this only matters if you have a machine with 4GB or more of ram, and want to install a 32 bit OS for some reason. Like maybe you already own a copy of XP 32 bit, or you use linux, and things break when you use the 64 bit version. I have an Atom 330 with 4GB or ram, and use 32 bit OSs.

I hope that clears things up.
do you have to manually enable it?
I manually enabled my workstation for 4gb, windows 7,noticed nothing at all.. safe to assume common sense finds that it is 4gb and the os deals with it accordingly? or does something need to be done?

ilovejedd
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Post by ilovejedd » Mon Aug 16, 2010 10:51 am

I thought only Windows Server supported PAE (at least on the Windows side) so they can use higher than 4GB RAM?

~El~Jefe~
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Post by ~El~Jefe~ » Mon Aug 16, 2010 5:03 pm

thanks. pimp info.

Matthew
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Post by Matthew » Mon Aug 16, 2010 6:34 pm

Glad I could help. :)

@colm: I don't have Windows 7, but in XP, as long as you turn on 'data execution prevention' you also get PAE. I think it's on by default. If it's working, you'll see it on this screen.
Image
Mine doesn't say 4GB or ram because my ION graphics are using some of it.

@ilovejedd: Here's a list of versions of windows that support PAE, and some instructions to enable it if the 'data execution prevention' thing doesn't work.
I haven't tried them though.
http://msdn.microsoft.com/en-us/library ... 85%29.aspx

colm
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Post by colm » Tue Aug 17, 2010 8:43 pm

hey yes, I had to enable. I thought that stopped with xp as well.. but the DEP has to be hardware capable, I am on an old prescott workstation with windows 7.

I did the usual routine:

bcdedit /set pae forceenable

and it did take a little while. My test is corel video studio.. if it is stuck at 564 mb it is not using all memory, when pae finally enables it climbs to 700 something and bounces around. (don't laugh, that is my only test)

the vid card with 512mb confuses something over the 4gb mark , I have 4gb installed.. and there is an 8mb rom usable by an admin...etc etc.
I know just by browsing the net, the hep for individual programs is larger (ie: internet explorer)

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