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View Full Version : 4Gigs Of Ram for 32bit OSes.


Mr Bigman
08-26-07, 09:09 PM
This isn't totally true that a 32bit OS only sees 3.2 gigs of ram.

At work we had a Compaq Prolient Server with 4 gigs of ram and Windows 2k server SP4.

The OS showed all 4 gigs of ram in the task manager and used it like it supose too.

That should be said the same for XP since its 32bit also and built on the same platform as Windows 2K.

ALot of folks here say there XP rigs with 4 gigs of ram say 2.39 gigs or ram or 3.2 gigs of ram when i should say 4096 gigs of ram.

The Compaq Prolient that we had at work was a quad Zeon 800MHZ with 4 gigs of ECC PC 133 Ram so why not this new hardware?

XDanger
08-26-07, 09:25 PM
2k server can "see" upto 4gb I think , Its a server os after all.
http://www.microsoft.com/whdc/system/platform/server/PAE/PAEmem.mspx

I was looking at some post earlier that said they took out 4gb addressing from xp ??? maybe some illinformed poster, I dont know .

Either way , Ive got PAE turned on and my 32bit XP is only showing me 2gb at the moment ?
2096mb to be exact ,which sounds wrong.

"The maximum amount of memory that can be supported on Windows XP Professional and Windows Server 2003 is also 4 GB. However, Windows Server 2003, Enterprise Edition supports 32 GB of physical RAM and Windows Server 2003, Datacenter Edition supports 64 GB of physical RAM using the PAE feature."
"Physical Address Extension. PAE is an Intel-provided memory address extension that enables support of up to 64 GB of physical memory for applications running on most 32-bit (IA-32) Intel Pentium Pro and later platforms. Support for PAE is provided under Windows 2000 and 32-bit versions of Windows XP"

$n][pErMan
08-26-07, 09:53 PM
I think the 4GB issue is not the RAM in a 32bit OS but rather the addressing space. Video card memory uses part of the 4GB space along with a bunch of other stuff I can't recall at the moment but I am sure someone else could spout off quickly. :)

rflair
08-26-07, 10:36 PM
Actually it is true, 32bit OS's, all of them can only see up to 4gigs. What MS did on some of thier 32bit server OS's was add mappable extensions in, the OS was written to see 4+ gigs and there are programs under 32bit which will also see 4+ gigs but they have to be specially coded to do it, all in all not a very elegant way of doing things, move to 64bit.

john19055
08-27-07, 02:52 PM
I think a server would be able to use 4 gigs ,but os's like winxp32bit and vista32bit really only use 2 gigs ,I can install my 4 gigs of PC8500C5D but it only shows 2.75 gigs ,and as far as performance I see no difference in performance with 4gigs,so I see no point in useing 4gigs with a 32bit os unless it is a server os .

Slammin
08-27-07, 03:44 PM
2.75gig is 750mb more than 2 1gb sticks and I have stuff that actually uses the extra unter XP.

john19055
08-27-07, 07:45 PM
I put them back in and now it just shows 2.25 but I think it just uses 2gigs ,because I see nowhere where it helps ,maybe it does do something ,but games load no faster ,it does'nt copy no faster.IMO if you want to use four gigs then use a 64bit OS.

stncttr908
08-27-07, 07:55 PM
2^32 = 4,294,967,296/(1024^3) = 4GB. However your OS has to worry about paging, etc., so that is why you don't get a full 4GB physical. There simply isn't enough room to address it all under a 32-bit architecture.

SignorSalad
08-27-07, 08:26 PM
You can have 4gb of ram, but any one program can only access 2gb of virtual address space.

http://www.anandtech.com/systems/showdoc.aspx?i=3060

Slammin
08-28-07, 10:29 AM
I put them back in and now it just shows 2.25 but I think it just uses 2gigs ,because I see nowhere where it helps ,maybe it does do something ,but games load no faster ,it does'nt copy no faster.IMO if you want to use four gigs then use a 64bit OS.


If you don't run anything that needs extra memory, you won't see much benefit in adding extra memory. Still, it seems like I get higher synthetic bechmarks when using 4 sticks and I think this has to do with memory interleaving, but that by itself should probably not be a real reason to go with 4 sticks. Plus, most of the time when you use 4 sticks, overclocking ram becomes more difficult.

I primarily run Vista64, so it's all good here.

XDanger
08-28-07, 03:02 PM
What about my 2gb in 32 bit xp pro when using 4gb with PAE turned on in bios ,Could it be that my boot.ini switch is off as I have xp on a bad vista installs boot.ini file ?

I have to select older version of windows but theres no proper vista there on that drive.
I cant change the boot file from xp because it belongs to the broken Vista.
At least I think I cant.

rhink
08-28-07, 08:45 PM
with PAE a 32 bit OS and CPU can 'see' up to 64 gigs, but as someone else posted, only 2 gigs per app (unless you do some funky paging in the app). Everything since the P6 (Pentium Pro on up) uses essentially a 36 bit address bus.

ynnek
08-29-07, 03:27 AM
http://msdn2.microsoft.com/en-us/library/bb147385.aspx

Differences in Addressable Memory

The first thing most developers notice is that 64-bit processors provide a huge leap in the amount of physical and virtual memory that can be addressed.

* 32-bit applications on 32-bit platforms can address up to 2 GB
* 32-bit applications built with the /LARGEADDRESSAWARE:YES linker flag on 32-bit Windows XP or Windows Server 2003 with the special /3gb boot option can address up to 3 GB. This constrains the kernel to only 1 GB which may cause some drivers and/or services to fail.
*

32-bit applications built with the /LARGEADDRESSAWARE:YES linker flag on 32-bit versions of Windows Vista, and on 32-bit versions of Windows Server Code Name "Longhorn" operating systems, can address memory up to the number specified by the boot configuration data (BCD) element IncreaseUserVa. IncreaseUserVa can have a value ranging from 2048, the default, to 3072 (which matches the amount of memory configured by the /3gb boot option on Windows XP). The remainder of 4 GB is allocated to the kernel and can result in failing driver and service configurations.

For more information about BCD, see Boot Configuration Data on MSDN.
* 32-bit applications on 64-bit platforms can address up to 2 GB, or up to 4 GB with the /LARGEADDRESSAWARE:YES linker flag.
* 64-bit applications use 43 bits for addressing, which provides 8 TB of virtual address for applications and 8 TB reserved for the kernel.

Beyond just memory, 64-bit applications that use memory-mapped file I/O benefit greatly from the increased virtual address space. The 64-bit architecture also has improved floating-point performance and faster passing of parameters. Sixty-four-bit processors have double the number of registers, of both general purpose and streaming SIMD extensions (SSE) types, as well as support for SSE and SSE2 instruction sets; many 64-bit processors even support SSE3 instruction sets.

CaptNKILL
08-30-07, 08:18 AM
"Physical Address Extension. PAE is an Intel-provided memory address extension that enables support of up to 64 GB of physical memory for applications running on most 32-bit (IA-32) Intel Pentium Pro and later platforms. Support for PAE is provided under Windows 2000 and 32-bit versions of Windows XP"
:lol:

I want a Pentium Pro 150Mhz with 64gigs of ram running Server 2003. :lol:

crainger
08-30-07, 09:25 AM
:lol:

I want a Pentium Pro 150Mhz with 64gigs of ram running Server 2003. :lol:

Nice piece you'll have there. (lee63)