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32-Bit Windows and 4GB of RAM

Getting 32-bit Windows to recognize anything beyond 2GB of installed RAM is a seemingly futile effort. Even if your hardware supports the possibility, the software may hold you back - and performance gains are questionable:

The reduction in available system memory depends on the devices that are installed in the computer. However, to avoid potential driver compatibility issues, the 32-bit versions of Windows Vista limit the total available memory to 3.12 GB. If a computer has many installed devices, the available memory may be reduced to 3 GB or less. However, the maximum memory available in 32-bit versions of Windows Vista is typically 3.12 GB.

So, people use a PAE switch to get past the imposed 2GB barrier. Here’s a description of the 4 GB RAM Tuning feature and the Physical Address Extension switch:

When the /3GB switch is used with Windows XP Professional, with Windows Server 2003, Datacenter Edition, with Windows Server 2003, Enterprise Edition, the /3GB switch works identically across versions. This functionality lets device-driver developers test their drivers in this configuration without having to install one of the Windows Server 2003 products just listed. The user-mode memory space is now limited to 3 GB.

Sounds good, right? Not so fast:

The /3GB switch can cause some applications to have problems that are related to address dependencies or to a reduction in kernel space.

Bottom line: if you have 4GB of RAM in your system (or more), and you want to take full advantage of it, start using a 64-bit OS.

16 Comments

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I was thinking of buying 4gb of RAM for my Acer Aspire 3680 but then I asked myself “This laptop isn’t THAT powerful.”, So then I just decided to stick to 1gb of RAM. Even if I do buy 4gb of ram for my laptop, I would then probably switch to a 64 bit Linux because it’s simply much more better then running a 64 bit version of Vista.

And this has been a limitation of the 32-bit Intel architecture. It is not just a Windows issue, as in my former life as a NetWare Administrator, anything above 4GB was just swap for the OS.

Your bottom line has been the case for the last few years. Want to make use of that 4GB (or more) of memory, get a 64-bit OS.

I think that very people will actually use 4GB of memory, 2GB is definitely enough for now. But, if you do need 4GB of memory, you should simply pick up an OEM copy of Vista or another 64 bit OS. Plus, if you are building a new computer, you may as well go for the 64 bit version anyway, there aren’t really too many compatibility issues from what I have heard. Slightly unrelated, but probably relevant. I am still waiting for that service pack! Good that is going to be out very soon.

dalambomanblog.blogspot.com

Whoa, big problem in this post. the /3GB switch has NOTHING to do with available RAM, detection of said RAM, or any limits on memory in the OS. It has nothing to do with PAE. Nothing.

DO NOT use the /3GB switch. It will cause crashes. It will make your machine unreliable. DO not use it.

Details: http://blogs.msdn.com/oldnewthing/archive/2004/08/05/208908.aspx
http://blogs.msdn.com/oldnewthing/archive/2004/08/06/209840.aspx
http://blogs.msdn.com/oldnewthing/archive/2004/08/09/211356.aspx
http://blogs.msdn.com/oldnewthing/archive/2004/08/11/212720.aspx

Also, the /PAE switch, which I think you meant to copy from that (confusing and possibly misleading) article - is not necessary in Windows XP SP2 or Vista, as PAE is always enabled.

Lastly, this has nothing to do with Vista. Every single 32-bit OS encounters this same limitation. It’s a limitation of the 32-bit address space. It’s as simple as that.

[...] new hardware? Well, I blame it all on RAM. 32 bit versions of any OS only address 4GB of RAM (and not even all of the 4GB.) I need lots of RAM to run the virtual machines I use to prototype client solutions, test [...]

am running Vista64 bit with 5Gigs of RAM. itunes is running fine but i have several thousand albums and artwork. when i scroll through my albums using coverflow, itunes starts eating RAM like crazy which is fine because i have a lot but when itunes has used 2.96Gigs of my 5Gigs of my ram it freezes and stops working. The rest of the OS still functions fine. I can terminate itunes and restart and it is fine but i am unable to scroll my library casually without it hitting this 2.96Gig wall. I am sure it is just a matter of a Registry key needing to be edited but i don’t know where to look for the Reg entry. Any help is appreciated.

Thanks

Powel

Itunes should not take 2.96 GB of ram. Hell, it shouldn’t take half a GB of RAM. This might be a program bug so contact Apple and tell them about your problem. They should be able to fix that up.

Out of sheer need for a powerful gaming computor i was wondering this. A few of my computer friends said that 64bit os for either xp or vista was full of bugs and not worth it. Also, i was told by a few people that 32 bit could recognize 4gb of ram, minus your video cards memory, typically leaving around 3.5. I was at first looking at a rediculous 6-8 gb, but if only 2 is recognized then whats the point. All in all i was wondering of the stability of the 64 bit os because of its ram capacity

Nolan, if you want to be awed by amazing frame rates/resolutions of the latest 3D games then spend a fortune and “go 64″. However you will not have much time to play due to spending your time pulling your hair out with the frustrations of constant fixes, driver updates, crashes etc.

If you want to actually play the games then go for a *quality* 32-bit set-up - all good quality parts espesh motherboard, 2 GB memory and almost-top-of-of-the-range video/gfx. The reason I say don’t buy top-of-the-range is because it’s a lot more money for not much more performance. Use 2 hard-drives - one for the OS, one for everything else, install fresh Windows XP SP2 (not Vista) and turn all the awful stuff off i.e. hibernation, system restore etc. then Enjoy :)

The ultimate in frames/second is less important than enjoyment :)

[...] in the other thread? here read this I think you’ll find everything you need to know here http://chris.pirillo.com/2007/08/30/…nd-4gb-of-ram/ [...]

4GB is overkill its not posseble to juice more then 2GB on a 32bit OS even if you have 3GB it will onley juice 2GB cause the 32 bit OS cant adress more then 2GB to an application
there where some updates that the OS shows there 3,12GB max but its onley for a good look not for juice

sow having 3GB onley make you future proof for 64bit OS

Certainly, up as far as Vista SP1, Vista 64bit was the most time-wasting unstable piece of S/W I had every seen on a computer. I can’t speak for 64+SP1 because by the time it came out I had dumped 64 and gone back to 32. What I can say is I had experienced some of the same issues also with 32, but, with SP1 and all current patches for it seems improved. I still have problems, but nothing as regular as earlier this year when I first tried Vista.

The time wasted with both versions, in particular the long drag after many many many many reboots (because it was unstable) for the O/S to get loaded and back in operation again was enough to turn me off MS OS’s for good. For many people MS is probably living on borrowed time - the “let the customer do the testing approach” is simply not satisfactory when people expect a production ready OS out of the box.

The organisation I work for employs >250,000 people and is moving towards a Linux desktop - most of our apps. are already available on Linux, or, as Web Based applications so I don’t imagine the final nail is far off.

One problem with 64 is that whist it will allow you access all of your 4GB on a laptop, you will still mostly be running 32bit SW on it (who’s writing 64bit specific apps. for Windows?). This means you’ll be caching Windows 64 and 32 bit libraries and 32 bit applications. Today what people probably want is more addressable memory, not necessarily bigger address space per process. We are running more apps., not bigger apps.

I believe people are incorrect when they say the only way to get 4GB and above is to go with a 64bit OS. Let’s face it, Windows Server 32 bit can access all of the RAM using 36 bit addressing. There appears to be no reason, other than marketing, that MS are not giving us > 4GB (eg: full PAE capability) on Windows Vista (esp. Ultimate).

Today, I’d prefer to have a 32bit OS with >4GB than a 64bit OS. I believe current 32 bit linux distros. will normally handle 36bit addressing properly. When I’m comfortable I can build, backup, restore & recover SUSE correctly with all drivers for my T61, I’ll be saying goodbye to Vista.

If you are using multiple applications that are memory intensive, will the 32bit OS address the entire 4gig of ram? From what I can find, the limitation is 2gig per process.

[...] 32-Bit Windows and 4GB of RAM August 30, 2007 - 4:00pm Getting 32-bit Windows to recognize anything beyond 2GB of installed RAM is a seemingly futile effort. (…)   [...]

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