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32-bit and 4gb memory limitation????

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December 4, 2008 1:46:35 PM

Folks,
I just about to upgrade my PC. I'm going for 3Gb tri channel memory and the 4870X2 amongst other things. My question is I know 32-bit can only address around 4Gb of RAM, however with 3Gb RAM and 2Gb video memory making 5Gb will Vista 32 not recognise all that RAM? Or does your main RAM and video memory work independently making Vista 32 suitable for my needs?

Thanks.
December 4, 2008 2:02:11 PM

1.) why are you even bothering with Vista 32? It was made for legacy hardware in mind (Think Pentium 4s and Athlon XP).

2.) Are you getting a Core i7 platform? It's really a waste to get only 3GB of memory on a Core i7 platform.

And to answer your question, yes it will limit you some, probably recognizing around 2.5GB-2.7GB of memory.
December 4, 2008 2:15:58 PM

Video memory is separate. Any 32-bit OS should recognize the full 3 GB of system RAM.
Related resources
December 4, 2008 2:16:46 PM

Welcome back Strange. To answer the question The PC cannot use the RAM on the GFX card (only the GFX card can). So if you install 3 GB of RAM, That is what you get (minus what the system/GFX card uses) to anywhere from 2.2 to 2.7 usable by the PC. Take the suggestion use a 64bit OS (don't bother with Ultimate, I'm paying for that mistake), that way you can install as much RAM as you want (limited by the MB of course).
December 4, 2008 2:32:55 PM

emp said:
1.) why are you even bothering with Vista 32? It was made for legacy hardware in mind (Think Pentium 4s and Athlon XP).


Very Good question !! I just made the switch from XP32 to Vista64 and everything works just fine, hardware and software. I really don't understand why so many people install Vista32 on brand new systems.
December 4, 2008 2:53:46 PM

emp said:
1.) why are you even bothering with Vista 32? It was made for legacy hardware in mind (Think Pentium 4s and Athlon XP).

2.) Are you getting a Core i7 platform? It's really a waste to get only 3GB of memory on a Core i7 platform.

And to answer your question, yes it will limit you some, probably recognizing around 2.5GB-2.7GB of memory.


Alot of people i've spoken to say there are lots of games that won't run of Vista 64. Is this true? Also I am getting the i7 920 but why is it a waste to only get 3Gb? I know people always bang on about Crysis but task manager is only using 1.2Gb on my current system so i was thinking 3Gb would be plenty for now. Am I missing the point?
December 4, 2008 3:13:01 PM

I've had no problems with games either with Vista64.

4gb is the minimum for smooth operation in Vista. If you have the budget go for 6gb as you are getting an i7. I will upgrade to 8gb probably after the holiday season.
a b à CPUs
a b } Memory
December 4, 2008 3:29:12 PM

I'm assuming that is 1.2GB just idling (with nothing open). Many games an really gobble down ram (besides Crysis). My current Vista 32 is tweaked down so it only uses 400MB or less with nothing open, yet it can still start running low on ram (I have 2 GB). That's why I'm going to Vista 64 and 4GB in my next build. I think 64 is fairly stable now. Do you have both versions (32 and 64)?
December 4, 2008 3:57:36 PM

Kkkk1 said:
Alot of people i've spoken to say there are lots of games that won't run of Vista 64. Is this true? Also I am getting the i7 920 but why is it a waste to only get 3Gb? I know people always bang on about Crysis but task manager is only using 1.2Gb on my current system so i was thinking 3Gb would be plenty for now. Am I missing the point?

take it from a hardcore gamer, A LOT of games run on Vista 64. it depends on what games you're talking about and how old? All my games run fine with no hitch at all. the people you talked to are either never tried Vista64 before or they are playing games made in the 90's which in that case i'm not sure.

starcraft is probably the only 10 year old+ game i play and it's fine on Vista, anything older than that, i don't know, anything newer works like a charm. 4gb is the new standard for DDR2 ram since it's so cheap, but if you're going to build an i7 build, you have to go with 6gb. you'll most likely end up upgrading to 6gb later from the 3gb.
December 4, 2008 4:19:24 PM

WR said:
Video memory is separate.


Traditionally, video memory was mapped into the CPU address space so that the CPU could write directly to it (e.g. for transferring large textures over or for writing video data to an offscreen buffer). I don't know whether that's still the case now that cards can have 1GB+ of RAM rather than 64MB.

Obviously if you have 2GB of video memory mapped into your CPU's address space in the first 4GB range then you can't use more than 2GB of system RAM.
December 4, 2008 4:27:47 PM

Kkkk1 said:
Alot of people i've spoken to say there are lots of games that won't run of Vista 64. Is this true? Also I am getting the i7 920 but why is it a waste to only get 3Gb? I know people always bang on about Crysis but task manager is only using 1.2Gb on my current system so i was thinking 3Gb would be plenty for now. Am I missing the point?


I've had pretty much the same experience as aznguy. The only games I have that won't run on Vista64 are so old that they require single core processors, and I've long since gotten rid of my last single core processor. I totally agree with those who say to get Vista64 over Vista32. There is no sensible reason to put a 32 bit OS on a modern computer.

While 3 gig of ram isn't a waste, it will limit you very quickly and slow down the game play as you end up using the hard drive as virtual ram. This situation will only worsen as the years go by and games get even more complicated. Get the 6 gig package and be happy.
December 4, 2008 6:58:57 PM

sailer said:
I've had pretty much the same experience as aznguy. The only games I have that won't run on Vista64 are so old that they require single core processors, and I've long since gotten rid of my last single core processor. I totally agree with those who say to get Vista64 over Vista32. There is no sensible reason to put a 32 bit OS on a modern computer.

While 3 gig of ram isn't a waste, it will limit you very quickly and slow down the game play as you end up using the hard drive as virtual ram. This situation will only worsen as the years go by and games get even more complicated. Get the 6 gig package and be happy.


OK I think the consensus is get Vista 64 which i'll have to do. At the moment I run XP pro so will have to buy Vista. Also while 6 Gb of ram would be nice I really don't think my budget will allow at the moment. I suppose I could drop the 4870X2 and go for 48701Gb and get the extra RAM then add another 4870 at a later date. Does anyone think that might be the better option? Or just use 3Gb now and upgrade to 6Gb later?

Many thanks for all your posts.
Anonymous
a b à CPUs
a b } Memory
December 4, 2008 7:20:22 PM

video ram IS NOT SEPARATE... its an urban legend it is separate...

If you install 3 gigs of ram with the 4870 x2 you'll see a total of about 2.2 - 2.5 gb of physical ram

First the 32 bit operating system can address max of 3.5 gb of ram... generally more like 3.2 gb after all is said and done... then... 1 GB of vram is subtracted (1 gig and not 2 since the video card doesn't actually use 2 GB)

AND WALAH!!! you come out to your magical number



About your budget... if you don't have enough to get what you want... DONT GET IT... save up for another month... spend the under 100$ and get 6 GB of ram... your getting an x58 platform what do you expect?
December 4, 2008 7:20:22 PM

Regaring your video card question it really depends on what games you play and also what resolution. And also how long do you plan to keep the card ? I change video cards every 6 to 9 months.

For most games,if you play at 1280*1024 then a 4850 512 would be fine. 4870 512 will allow more eye candy. 4870 512 will even handle 1920*1200 with no problems at all.

I have a 4870 512 and I play @ 1920*1200. Games I play right now are COD4, Fallout3, FarCry2 and they all run great, mind you I only use 2xAA which I think is more than enough at that resolution.

Again the question is how long do you plan to keep the card ...
December 4, 2008 7:56:23 PM

only problem i have run in to is crossfire stutter but it could have been that it was 4870 with 4850
December 4, 2008 7:56:30 PM

Kkkk1 said:
Folks,
I just about to upgrade my PC. I'm going for 3Gb tri channel memory and the 4870X2 amongst other things. My question is I know 32-bit can only address around 4Gb of RAM, however with 3Gb RAM and 2Gb video memory making 5Gb will Vista 32 not recognise all that RAM? Or does your main RAM and video memory work independently making Vista 32 suitable for my needs?

Thanks.

With a 2GB graphic card you will be down to 1.5-1.7GB ram. Reason is that the graphic card needs the addresses, and these two GB on top is chewed away. So get a 64Bit Vista and the cards Addresses will be put far out ot your memory range.
a b à CPUs
December 4, 2008 8:13:16 PM

Quote:
video ram IS NOT SEPARATE... its an urban legend it is separate...

If you install 3 gigs of ram with the 4870 x2 you'll see a total of about 2.2 - 2.5 gb of physical ram

First the 32 bit operating system can address max of 3.5 gb of ram... generally more like 3.2 gb after all is said and done... then... 1 GB of vram is subtracted (1 gig and not 2 since the video card doesn't actually use 2 GB)

AND WALAH!!! you come out to your magical number



About your budget... if you don't have enough to get what you want... DONT GET IT... save up for another month... spend the under 100$ and get 6 GB of ram... your getting an x58 platform what do you expect?

Quote:
First the 32 bit operating system can address max of 3.5 gb of ram
This part is incorrect. Actually a 32 bit os can address 4 gig of memory! THEN you minus the other devices that have ram on them such as video ram. This is how you end up with typical amounts of 3 to 3.5 gig. 2 to the 32 power is 4 gig, that is the 32 bit limit. If you have a massive amount of video ram this might dip your 3 gig system down below 3 gig of usable ram.

If you are correct about a 2 gig video card not using all of it and only using 1 gig then it seems possible that on a 3 gig system you will be able to use all or nearly all of your 3 gig of system ram. If a CF or x2 card only uses 1 gig is what I simply don't know.
Anonymous
a b à CPUs
a b } Memory
December 4, 2008 8:21:27 PM

the most i've ever seen it address with a integrated graphics card is 3.5 gb of ram... never seen it address more space than that (integrated graphics had like no ram either :na: )

Either way thank you for your correction :) 
December 4, 2008 9:49:20 PM

First, I'll reply with what Vista SP1 32-bit reports to me on System A. I have 2 x 2 GB RAM installed and a 3072MB page file. Video card is a GTX 280 (1 GB VRAM) and resolution is 1650 x 1080 32-bit. Firefox and a few background apps are running - consuming 110 MB RAM under Task Manager.

Physical Memory (MB)
Total 3070
Cached 2257
Free 132

Page File 996M/6039M


Next, System B has 2 x 512 M and 2 x 1G for exactly 3 GB of installed RAM. Page file is set at exactly 1536M (or 1.5 G). GPU is a Radeon x1900xtx (512 MB VRAM), set at the same 1650 x 1080 resolution. This one runs Windows 2000 Professional SP4. Firefox and a DX7 app with background processes are open - using ~200 MB RAM.

Physical Memory (K)
Total 3112172
Available 2542800
System Cache 610740

Commit Charge (K)
Total 669380
Limit 4553604
Peak 670612

With two copies of Prime95, I'm able to load almost the entirety of remaining physical memory on either system with no persistent thrashing. (Windows always frees up a little extra space, so task manager would say ~2.98G used.)

3039.2 MB RAM displayed with 3072 MB installed, using a 512 MB video card.

3070 MB RAM displayed with 4096 MB installed, using a 1024 MB video card.

At least I fail to observe something approaching the 2.2-2.7 GB region that others are mentioning. Does anyone have something closer to the OP's system than my System B?

Thogrom's 3.5 GB theory would explain my System B if only System A reported 2.5 GB available, since it has a full 1 GB video card.

Quote:
4gb is the minimum for smooth operation in Vista.

Quote:
Also while 6 Gb of ram would be nice I really don't think my budget will allow at the moment.

That is the primary reason I'm on 32-bit Vista. 3 GB under 32-bit is like at least 4 GB under 64-bit. You spend more money on RAM to have the same effective space under 64-bit. If you need the space, you have no choice. I just don't need it yet.
a b à CPUs
December 4, 2008 11:11:44 PM

Quote:
the most i've ever seen it address with a integrated graphics card is 3.5 gb of ram... never seen it address more space than that (integrated graphics had like no ram either :na: )

Either way thank you for your correction :) 

We are not talking about integrated graphics cards.

A 32 bit OS can generate 4 gig of addresses (2 to the 32 = 4 gig) so 4 gig is the total address space the OS can work with. Since the OS must address video ram (and the ram on other devices) it must reserve some of its 4 gig total addresses for those devices. It takes this address space of the top off the 4 gig of addresses (not off the top of your 4 gig of system ram, no system ram is being used here, it only goes UNUSED) and leaves the rest of the address space for system ram. The one gig or so of system ram that goes unused in a 4 gig system is not being used by video or anything else, it just sits there totally wasted because the OS simply does not have the addresses available to fill it up. Integrated graphics is a different case because integrated graphics actually uses system ram, it shares it with the system. This too reduces your total ram but for a different reason.
Gaming systems don't often have integrated graphics using shared ram. They have dedicated ram on the card. The amount of dedicated video ram will be subtracted from your 4 gig of address space, however, if you only have 3 gig of ram on your system that extra gig of address SPACE is not needed, hence you usually lose little or none of your three gig of installed system ram even when you have a lot of video ram, up to about 600 meg or so. If you have massive video ram you can even lose a sizable chunk of ram from a three gig system.
Anonymous
a b à CPUs
a b } Memory
December 5, 2008 12:17:03 AM

And that ^ is why I am still a teen, can't write coherently for long :na: 

Nice post :)  really clears it up for the thread, I'd actually refer back to that post if this ever comes up again, but considering the search function on tomshardware sucks... probably won't happen.
December 5, 2008 1:13:00 AM

Yeah, that and GenRabit's link really explain the issue. Except for this lingering question. Does the 4870 x2 at 1 GB per core count as 2 GB or 1 GB of addressable space?

A valid test would be any 32-bit Windows OS, a 4870 x2, 3+ GB installed RAM, and a task manager SS. Anyone?
December 5, 2008 2:33:48 AM

WR said:
Yeah, that and GenRabit's link really explain the issue. Except for this lingering question. Does the 4870 x2 at 1 GB per core count as 2 GB or 1 GB of addressable space?

A valid test would be any 32-bit Windows OS, a 4870 x2, 3+ GB installed RAM, and a task manager SS. Anyone?


Probably two. After all the two cores won't show the same.. One renders the upper part, one the lower.
December 5, 2008 2:46:04 AM

notherdude said:
Actually a 32 bit os can address 4 gig of memory!


Actually, a 32-bit x86 OS can address 64GB of memory, but 32-bit desktop Windows versions won't.

The 4GB limit is per-application, but the CPU can handle 64GB of physical memory; Microsoft only allow that on server versions of Windows. 32-bit PAE Linux kernels, for example, can manage 64GB of RAM.
December 5, 2008 3:31:21 AM

PAE is Physical Address Extension. It is a CPU feature that an OS can choose to use or ignore (for compatibility reasons). It's only arbitrary that the extension is only 4 bits; Intel designed it that way.

What you mean is almost every 32-bit x86 chip since the Pentium Pro has a special 36-bit addressing mode.

A 32-bit OS on a CPU without PAE wouldn't be able to address past 4 GB. It's not in the nature of a 32-bit OS to address past 4 GB of main memory. Doing so requires hardware and device driver support.

Quote:
Probably two. After all the two cores won't show the same.. One renders the upper part, one the lower.

See, I don't like guessing on this because there is an even stronger argument. The 1 GB framebuffers for each 4870 are mirrored and then each core can read its own copy to render its top or bottom half, or every other frame, or however the user sets the rendering mode. Since you have 1 GB effective VRAM, the OS should have no reason to be addressing 2 GB, right?
December 5, 2008 4:26:56 AM

Does this interesting ram functionality only apply to Vista? This approach is news to me although I have been stumbling over bits of it here and there for a while now.

The above system B looks pretty normal; but the Vista version is like pretty foreign.

I have been out of the loop for a few years and I have been researching hardware for a while, planning new system - and that will be AMD btw cos I can't support antitrust monopoly etc. AND I certainly would tend to discourage anyone who is not tekky inclined from investing in nejalem for the purpose of e-penis elongation or other ego related fantasy cos it's too new too expensive and you are headed for tekno hell or at least a very interesting time requiring a lot of patience and learning the hard way.

But this is not about hardware and I think it's a Vista thing. Kinda like microsoft takes us closer again to server tek, as they did with XP. At that time M$ intro'd new ACPI and caused a lot of obsolete hardware. It was published pre xp release, and so the hardware mftrs were warned and had to comply.

So IF THIS IS VISTA, has microslop published KB's about this?
Is vista using virtual mem differently?
Am I in the ballpark????????
Does anyone really know?

I am intending to go 64-bit OS - esp. with AMD cos AMD has been selling 64-bit processors for almost a decade. spintel is pretty new at it, and I think i7 is spintel first REAL 64 - the previous have either failed or been software instituted - fake. (amazing how nejalem near copies AMD's architecture)

The only info I had, before this posting by "notherdude", has indicated that 32bit OS will only show you 3.2 of 4 gigs - and I adopted that info, have shared that info, and decided to go 64-bit OS to avoid ram limits and wastage. But this is a whole different approach.

Another thing - I tend to study windoze and disable cleanly and safely a lot of useless features, as I am sure many others also do.
One tactic was to set virtual mem to NONE and then del the pagefile.sys. I wonder how Vista would respond to that treatment. The idea was, in gaming, to promote the use of fast ram rather than the use of comparitively slow hdd-access-speed virtual mem, not to mention the thrashing that occurs on the hdd with usage of v-mem. Idiot vista apparently loves virtual mem.

But I am still on xp and have basically no experience w wishta.

If anyone can further elaborate on what has been mentioned here, or link me to some crazy tek info or a kb or other site, that would be appreciated. Is there a name for all this that could be used to google? Any info thxx/

Thank you to notherdude for sharing.

sigh
.

EDIT = I just read the "Dan's" link - a very good read. I did not realize that the old dos 8086 era stuff was still in play in that manner. And the mem limits are well explained.
i still have a lot of questions about vista and esp. what happens if you kill the VM.

That brought back a lot of memories of things like
ECHO OFF
LH C:\DOS\EMM386.EXE /NOEMS
and trying to preserve that max 640K cos it determined the max program size you could run. Like DOOM.

A major issue in those days - no matter what kinda mess your pooter was in =
"Never mind you can't open Word 3, and you lost your resume cos it crashed before you saved it - Will DOOM still run?" :) 
= Nothing like having your priorities straight. :)  Things haven't changed much at all.

I remember having an IBM PS2 286 w 1 meg ram - you could HEAR every clock tick! :) 
December 5, 2008 4:41:49 AM

WR said:
It's not in the nature of a 32-bit OS to address past 4 GB of main memory.


So are you claiming that Linux is 'unnatural'?

Microsoft have PAE support for Windows, because it's available in some of the server versions; they just deliberately cripple the 32-bit desktop versions to limit them to 4GB of physical memory. It's a hack, but it's better than not using >4GB of memory at all.
December 5, 2008 7:32:01 AM

EXT64 said:
I'm assuming that is 1.2GB just idling (with nothing open). Many games an really gobble down ram (besides Crysis). My current Vista 32 is tweaked down so it only uses 400MB or less with nothing open, yet it can still start running low on ram (I have 2 GB). That's why I'm going to Vista 64 and 4GB in my next build. I think 64 is fairly stable now. Do you have both versions (32 and 64)?

1.2 gig is when I've loaded XP pro and running Crysis in medium settings half way through a level!! So was assuming 3Gb under Vista would be fine. Judging by all the posts it appears i'm wrong and most people are saying get 6Gb.
December 5, 2008 7:54:13 AM

You need to educate yourself re the path your ego is taking you down. Listen and learn. Do research. Read all you can. Slowly. And not in forums. You are confusing yourself. Back to basics first. Otherwise you just keep stumbling around chasing other people's opinions. Buy a broken pc and take it all apart and then make it work - with only your own research.

- any thrift store -
cost = $5
what you might learn = priceless!
Then donate it to the thrift store :) 

Then do it with your old pc.
Then a friends pc.
Don't quit till they all are perfect.

Then build your own basic functional unit. Then add to it.
(what's a basic functional unit?)

Either that or buy a dell. better to buy a busted dell.

Good luck.
December 5, 2008 8:09:40 AM

Sod this, i'm going for the following:-
Vista 64
6Gb DDR3 tri channel
X58 mobo
i7 920
GTX 260 216core
Corsair 1000W PSU, as i'll SLi later
22In TFT

Job done. Thanks for all the advise.
December 5, 2008 11:46:32 AM

MarkG said:
Actually, a 32-bit x86 OS can address 64GB of memory, but 32-bit desktop Windows versions won't.

The 4GB limit is per-application, but the CPU can handle 64GB of physical memory; Microsoft only allow that on server versions of Windows. 32-bit PAE Linux kernels, for example, can manage 64GB of RAM.


Windows XP and Vista has a 2GB limit per application under 32bit. Passing that limit and application is about to crash.


And 32bit os can only handle 4GB. The PAE extension use is an ugly path to walk down. The way I understand it, is that with an OS using the PAE, your still only have access to 4GB, but you can swap between "4GB" blocks..

To me this sounds like a nightmare, and I'd say go 64bit.
a b à CPUs
December 5, 2008 1:29:08 PM

MarkG said:
So are you claiming that Linux is 'unnatural'?

Microsoft have PAE support for Windows, because it's available in some of the server versions; they just deliberately cripple the 32-bit desktop versions to limit them to 4GB of physical memory. It's a hack, but it's better than not using >4GB of memory at all.



The story goes that at one time you could enable PAE to make more RAM available in XP but it caused too many problems, possibly because of poorly written drivers IIRC, this may or may not be the case but unless you can offer more proof I think it is a bit unfair to say that MS made this limit arbitrarily. A server OS is not likely to run the same vast range hardware of all makes and quality variables as a consumer version like XP, which may account for the difference there. It should be noted that a 64 bit OS costs no more than a 32 bit OS so at this point it is hard to see how this limitation could possibly profit MS much. Maybe before XP 64 was available, if your only choice was Server or XP, then yea, maybe. Maybe being the key term.

Mark Russinovich (author of process explorer and a MS tech fellow and brain) has something interesting to say on his blog on this subject:
Quote:
However, by the time Windows XP SP2 was under development, client systems with more than 4GB were foreseeable, so the Windows team started broadly testing Windows XP on systems with more than 4GB of memory. Windows XP SP2 also enabled Physical Address Extensions (PAE) support by default on hardware that implements no-execute memory because its required for Data Execution Prevention (DEP), but that also enables support for more than 4GB of memory.

What they found was that many of the systems would crash, hang, or become unbootable because some device drivers, commonly those for video and audio devices that are found typically on clients but not servers, were not programmed to expect physical addresses larger than 4GB. As a result, the drivers truncated such addresses, resulting in memory corruptions and corruption side effects. Server systems commonly have more generic devices and with simpler and more stable drivers, and therefore hadn't generally surfaced these problems. The problematic client driver ecosystem lead to the decision for client SKUs to ignore physical memory that resides above 4GB, even though they can theoretically address it.


Quote:
The consumption of memory addresses below 4GB can be drastic on high-end gaming systems with large video cards. For example, I purchased one from a boutique gaming rig company that came with 4GB of RAM and two 1GB video cards. I hadn't specified the OS version and assumed that they'd put 64-bit Vista on it, but it came with the 32-bit version and as a result only 2.2GB of the memory was accessible by Windows.


From here: http://blogs.technet.com/markrussinovich/

also from Mark:
Quote:
Because device vendors now have to submit both 32-bit and 64-bit drivers to Microsoft's Windows Hardware Quality Laboratories (WHQL) to obtain a driver signing certificate, the majority of device drivers today can probably handle physical addresses above the 4GB line. However, 32-bit Windows will continue to ignore memory above it because there is still some difficult to measure risk, and OEMs are (or at least should be) moving to 64-bit Windows where it's not an issue.
a b à CPUs
December 5, 2008 1:36:29 PM

Kkkk1 said:
Sod this, i'm going for the following:-
Vista 64
6Gb DDR3 tri channel
X58 mobo
i7 920
GTX 260 216core
Corsair 1000W PSU, as i'll SLi later
22In TFT

Job done. Thanks for all the advise.

You have chosen well for the future my son.
!