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Adrian Kingsley-Hughes
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Max memory limits for 64-bit Windows 7

By | April 28, 2009, 9:48am PDT

Summary: While the maximum RAM limit for 32-bit Windows 7 editions is 4GB, when it comes to 64-bit editions, the amount of memory that the OS can address depends on which edition you are running.

Special Report: Windows 7

While the maximum RAM limit for 32-bit Windows 7 editions is 4GB, when it comes to the 64-bit editions, the amount of memory that the OS can address depends on which edition you are running.

Here are the upper RAM limits for the different editions of Windows 7:

  • Starter: 8GB
  • Home Basic: 8GB
  • Home Premium: 16GB
  • Professional: 192GB
  • Enterprise: 192GB
  • Ultimate: 192GB

These limits are similar to those for Vista editions, expect that Vista Enterprise and Vista Ultimate have had their upper limits raised from 128GB to 192GB.

The one to look out for there is the 16GB limit on Home Premium. If you’re building a Core i7 system then it’s quite easy (if you have the cash!) to exceed this limit. As long as you’re aware of the limit and plan your OS accordingly you’ll be OK.

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Topics

Limit, Microsoft Windows 7, Memory, Microsoft Windows Vista, Edition, Microsoft Windows Vista (Longhorn), Microsoft Windows, 64-Bit, Operating Systems, Software, Processors, Semiconductors, Hardware, Components, Adrian Kingsley-Hughes

Adrian Kingsley-Hughes is an internationally published technology author who has devoted over a decade to helping users get the most from technology.

Disclosure

Adrian Kingsley-Hughes

All opinions expressed on Hardware 2.0 are those of Adrian Kingsley-Hughes. Every effort is made to ensure that the information posted is accurate. If you have any comments, queries or corrections, please contact Adrian via the email link here. Any possible conflicts of interest will be posted below. [Updated: February 23, 2010] - Adrian Kingsley-Hughes has no business relationships, affiliations, investments, or other actual/potential conflicts of interest relating to the content posted so far on this blog.

Biography

Adrian Kingsley-Hughes

Adrian Kingsley-Hughes is an internationally published technology author who has devoted over a decade to helping users get the most from technology -- whether that be by learning to program, building a PC from a pile of parts, or helping them get the most from their new MP3 player or digital camera.

Adrian has authored/co-authored technical books on a variety of topics, ranging from programming to building and maintaining PCs. His most recent books include "Build the Ultimate Custom PC", "Beginning Programming" and "The PC Doctor's Fix It Yourself Guide". He has also written training manuals that have been used by a number of Fortune 500 companies.

Adrian also runs a popular blog under the name The PC Doctor, where he covers a range of computer-related topics -- from security to repairing and upgrading.

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PageTable is the culprit
thandermax 8th Jun 2010
Limitation of MAX memory size depends on many factor,
first and foremost problem will be sheer level of Pagetable and it's size.

In case of 64bit memory for 4KB(2^12) page, no of entry will be 2^52. which is huge.

For 64 bit memory, pagetable will be splitted up into multiple level, without that to address 2TB memory , your page table will consume considerable amount of RAM.

Also any look up into that HUGE table will be slow.

CPU incorporates TLB (which is a cache memory of recently/frequently used page table entry), but 64 bit still a daunting challenge .

One way of reducing that table size will be using large page (4MB ?) .
View in thread
0 Votes
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I think a better question might be
chrome_slinky@... 28th Apr 2009
when we might start seeing memory densities that could make those limits 'limiting' in any way. I have not actually set eyes on any server board that will allow 128GB to be exceeded.

I'm sure they exist, if only on a drawing board, but in the wild, not yet.
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Here you go...
itguy08 28th Apr 2009
None of that Dell CRAP here:
http://www-
03.ibm.com/systems/x/hardware/enterprise/

Mainly great for VMWare, Linux, etc.
0 Votes
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I see the picture
chrome_slinky@... 28th Apr 2009
and read the PDF, but at the current density of memory, there would need to be 64 memory slots - there are not. So, as I was pointing out, the memory density makes using that much impossible.
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Here's one with 2TB of RAM.
ye 28th Apr 2009
http://blogs.technet.com/markrussinovich/archive/2008/07/21/3092070.aspx
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I didn't see it anywhere
chrome_slinky@... 28th Apr 2009
in words or pictures
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It was in the Task Manager screen shot.
ye Updated - 28th Apr 2009
First graphic. Spefically the 2046965 is highlighted.
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It's 2Gb, not 2 TB... [nt]
Coogol 28th Apr 2009
nt
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Sorry, it is 2 TB.
Joeman57 28th Apr 2009
The numbers are in MB not KB.
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thats a nice number, but
richvball44 28th Apr 2009
they don't indicate whether that is in, K, M,G or T
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RE: Max memory limits for 64-bit Windows 7
Ishkaboo Updated - 28th Apr 2009
http://www.dell.com/content/products/productdetails.aspx/server-poweredge-r900?c=us&cs=04&l=en&s=bsd

Uhhh Chrome... In Servers? That kind of density has been around for quite some time... And here is a new Dell R900 with 32 DIMM slots for a total of 256GB w/ 8GB DIMMs
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Why even do it?
CobraA1 28th Apr 2009
Frankly, I'd like to know: Why even have an artificially low limitation on the amount of RAM in an OS? Have it set to something near or at the theoretical maximum.

Geez, it's the same mistake we've been making from day one: "we'll never use that much RAM." A couple years later that amount of RAM looks trivially small.

Why do we have such a hard time learning from the lessons of the past?
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I recall reading that Microsoft only supports...
ye Updated - 28th Apr 2009
...configurations they're able to test. Thus the 192GB RAM "limit" is a result of their inability to find a workstation class system that can accomodate more than 192GB. This doesn't mean Windows can't address more than 192GB. It just means that Microsoft isn't willing to support such configuration since they haven't been able to test them.

As for the other versions...I don't like the artifical limits. But I guess they have to differentiate them some way.
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And yet
frgough 28th Apr 2009
in a previous post you gave an example of a 2TB server that can run
Windows.

So the original questions stands. Why the artificial limit? It can't be a
testing issue.
0 Votes
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And anyone with a modicum of reading comprehension can clearly see...
ye 28th Apr 2009
...where I wrote:

"Thus the 192GB RAM "limit" is a result of their inability to find a workstation class system that can accomodate more than 192GB."
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Isn't it obvious?
jmoleary 29th Apr 2009
It would seem obvious that is is a product differentiation issue. You pay for the premium product, you get the premium performance.

What is the big mystery? Every software maker in the world does this.
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You Mean..
bobiroc 29th Apr 2009
I can't buy programs Adobe Creative Suite Standard and expect to have all the features of Adobe Creative Suite Premium. Or I buy Quickbooks and cry because I do not have all the features of Quickbooks Pro?

That's just ludicrous.

Of course that's just a couple examples but I am sure there are many many more.
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Nothing special happens . . .
CobraA1 Updated - 28th Apr 2009
Okay, so they only do what they can "test."

But these days nothing special happens when you change the theoretical maximum. It's not like in the DOS days when you have to worry about conventional memory vs high memory and EMS vs XMS etc etc.

These days, it's all the same. Memory is memory. A memory location at the 6 GB position is no different from a memory location at the 200 GB position. If everything is working fine in a 196 GB system, I see no reason why larger systems in the future would be different.

The biggest worry I have, frankly, is the 8/16 GB limits in the Home editions. Surely at least those can be increased? I can create a system with more than 8 GB easily today.

Gamers especially may be annoyed that they may have to buy Professional because of memory limits.
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"Surely at least those can be increased?"
Ole Man 28th Apr 2009
Of course they can! Just purchase a "Pro" or "Premium License".

That's how Microsoft bleeds their "customers". By imposing artificial limitations until more licenses are purchased.
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One more part of their crippleware upgrade strategy
BillDem 29th Apr 2009
The artificial RAM limits of the crippled versions of w7 are just one more element of Microsoft's retarded marketing plan. You don't see this crap in other OSes. MS sux.
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Again it's what they're willing to support.
ye 28th Apr 2009
But these days nothing special happens when you change the theoretical maximum. It's not like in the DOS days when you have to worry about conventional memory vs high memory and EMS vs XMS etc etc.

I agree. There is nothing different. And I suspect the increased "limits" from Vista to Windows 7 were nothing more than Microsoft being able to test workstations with 192GB or memory. I doubt they did anything to the code to increase that limit.

As for the lower limits we're in agreement and I thought I had said so in my initial post.
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Not a problem for gamers
Joeman57 28th Apr 2009
how many games go beyond even 2gb right now? None that I know of. 8 or 16 gb is fine for the next year or two, beyond that we'll see.
Also, gamers do not run 20 things at once plus the game. Everything that can be shut off is shut off while gaming.
0 Votes
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GRID, Galactic Civilizations II, Crysis, pretty much every game . . .
CobraA1 28th Apr 2009
GRID, Galactic Civilizations II, Crysis, World of Warcraft, pretty much every game made in the past few years. If it's using high resolution textures, large polygon counts, or very large world sizes, you can pretty much guarantee it's taking up any memory you throw at it.

Stardock had a pretty big rant about how their game is pushing the limits of 4 GB of memory in 32 bit systems a while back. Even though it's not a hyper-realistic game like Crysis, the largest galaxy sizes can really eat up RAM.
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WoW is a terrible example
LiquidLearner 29th Apr 2009
As the graphics are extremely basic. I've got 8GB in my system and I can dual log WoW, with both clients at max settings, and I'm still using less than 3GB total, system-wide.
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Re: Limit on Home Premium
sullivanjc 29th Apr 2009
Gee, you don't suppose they're pushing for upgrades to ultimate version, do you?
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Yeah
bobiroc 29th Apr 2009
Because the very small percentage of people that would want/need (or afford) more than 16GB of Ram is so large that they want to force it on them.
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Maybe if you can afford that much RAM...
Zogg 28th Apr 2009
... someone figures that you can also afford to pay more for the OS?

Although that would be hideously cynical.

0 Votes
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Yup
bobiroc 29th Apr 2009
Someone is going to drop $400 - $600 on memory and then complain that they have to pay a bit more for an OS to support it.
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Linux: ???GB Max
no_zd_user_name Updated - 28th Apr 2009
But the real limitation is the design of the motherboard.

0 Votes
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pae kernel in 32 bit addresses it...
Christian_<>< 28th Apr 2009
Windows does not address all of the memory,
however Linux distro's with the pae kernel
will......

I am confused, how many Windows versions
do you need???

Starter
Walker
Running
Falling
Licensing

Broke
0 Votes
+ -
I'm confused as well..
xuniL_z 28th Apr 2009
how many different distros do you need?
Ubuntu, BlueCat, Hard hat, Debian, Gentoo, poo poo, Gentoo, Knoppix, MkLinux, Red Hat, Slackware Linux, Rock Linux, Susi, DeLi, White Glove, Yellow Dog, Gray Ham, Scrudgeware, blue Linux, Brown Turd Linux.....
And none of them are 100% compatible with each other with varying degrees of proprietary mixed in with each.....you think that is easier and better than Windows having 5 different versions? There was 5 versions of XP and nobody complained.

Also, Ubuntu has different "Mixes", so what's your point again? Yes Ubuntu needed a small version to run on netbooks, so does windows. Isn't that facinating?


wink
0 Votes
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Exactly
bobiroc 29th Apr 2009
People Complain about the many different versions of Windows but Linux has many many more and hell if most people know what the versions are for. At least Windows tries to name it with something that you can make a reasonable deduction of what the OS is for. I mean names like Windows Home, Professional, Ultimate and Windows Server are so confusing right?
0 Votes
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TRUE!!
Pembo 29th Apr 2009
Agreed!!
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You would be
hasta la Vista, bah-bie 30th Apr 2009
how many different distros do you need?

And none of them are 100% compatible with each other with varying degrees of proprietary mixed in with each....

Nonsense. If you save your home directory partition (you do know what that is, don't you?) it's compatible with all.

you think that is easier and better than Windows having 5 different versions? There was 5 versions of XP and nobody complained.

That's because the tablet, Media Center and 64bit versions were never big sellers. None of them really took off.

You bought a machine it was typically Home or Pro. That's it. They're the only ones that really counted.
0 Votes
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XP SP2 added PAE
LiquidLearner 29th Apr 2009
and they had intended to address over 4GB of memory on a 32 bit system. However because of driver and program issues, that were written by third parties, it was decided it was better for the user experience to not allow it. Unlike Linux where if you break something people "just have to get over it".
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x64 Starter?
Resplendent 28th Apr 2009
I thought there *was* no x64 of Starter, so how is there a limit for an edition that won't even exist?
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Even when motherboards only supported 16k of memory ...
kd5auq 28th Apr 2009
there were always third party memory boards that would expand the limit.
99% of current real world user needs are met with the current 3/4gig limit. The other 1% have other options.
The limits seem to be an "upgrade" path to nickle and dime you to death.
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Because no other company differentiates on features.
ye 28th Apr 2009
It's only limited to MS. Sheesh.
0 Votes
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Of Course They Do
p0figster 29th Apr 2009
Nobody is saying that there shouldn't be
differentiation, the problem here is that
they're limiting how much RAM you can use
instead of what "Extras" you get or what
programs comes with it.

Does Adobe CS Standard say, "We'll only let you
use 2Gb of RAM and your saved files can't be
bigger than 100Mb" or do they say, "Standard
doesn't have the following features..."

It's like buying a BMW 3 Series and finding out
that it only has a 3 gallon tank because, hey,
you didn't go out for the 5 series.

What's next from MS? Hard Drive limits? "Oh,
I'm sorry, you only have home premium, you can
only have a 160Gb hard drive and no external
devices can be connected. If you want your
printer to work you need to buy Ultimate".
0 Votes
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It's not my preference.
ye 29th Apr 2009
Nobody is saying that there shouldn't be
differentiation, the problem here is that
they're limiting how much RAM you can use
instead of what "Extras" you get or what
programs comes with it.

But it is one of the things Microsoft has decided to use to differentiate versions.
0 Votes
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To late to worry, too blue to cry..........
Ole Man 29th Apr 2009
Ford has already embraced Microsoft's policy of limiting hardware capabilities. See: http://news.cnet.com/8301-17912_3-10058797-72.html

Soon, Microsoft will be limiting ALL your cars abilities. Pay Microsoft, or else! Stay home (oh wait, you won't have a home.... unless you paid Microsoft).

Stay tuned. More Microsoft innovation on the horizon. Its ALL "to help you", don'tcha know?
0 Votes
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See
bobiroc 29th Apr 2009
You are ridiculous
0 Votes
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About Ford
bobiroc Updated - 29th Apr 2009
You truly are a cranky old man aren't you? First of all if you buy a Ford with that Key that can lock teenagers from speeding and other things it comes disabled and is up to the owner to enable it if they want. Yes it is a choice of the car owner. Secondly I think some may like that feature as we all know kids will be kids and try to speed and all that. From all your conspiracy theories that you spread I gather you live in your basement that you call your secret lair and think everyone is out to get you.

Sorry that was a bit off subject but as you can see from him digging up an article and not telling the whole truth he is just out to make people believe that big brother is trying to bring everyone down.
0 Votes
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Fools learn nothing from wise men
Ole Man 29th Apr 2009
but wise men learn much from fools.

Maybe that's why warnings fall on the deaf ears of fools?

Enjoy your new Ford. And don't mind feeding the Microsoft kitty.
0 Votes
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Fool...
Wolfie2K3 29th Apr 2009
Ya know... I read and re-read that whole article you linked. The funny thing, I could NOT find ONE mention of Microsoft. Not a ONE.

I did read how it was a FORD innovation. Ford did this, Ford did that.

Of course, only a paranoid schizophrenic would assume that Microsoft was somehow involved.
0 Votes
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Whats your point
bobiroc 29th Apr 2009
Are you trying to say that Ford is forcing this option on their customers? Because that is not true. Ford makes fine cars but I do not own one and if I did I could choose not to use that feature. The fact that you consider yourself a wise man and imply that I am a fool amuses me. I do not know what made you this cynical but I pity you. Are you one of those people that think the government is tracking everyone's every move and that they are spying on you. I didn't think they allowed computers in your wing of the "nut house".
0 Votes
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@Wolfie
bobiroc 29th Apr 2009
I think he made that assumption because Microsoft provides the "Sync" system for ford. He is just a paranoid old man that likes to spread is conspiracy theories and scare everyone. I bet he is one of those that spread those emails around that try to do the same thing. You know the ones that you look up on sites like snopes.com and they say its false. The emails that have subjects like telemarketers are getting access to cell phone numbers and stuff like that.
0 Votes
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Same thing
bobiroc 29th Apr 2009
Since you decided to use Adobe as an example lets stick with that shall we. Adobe makes all sorts of products what Microsoft is doing to differentiate the versions of Windows is no different if you think about it. Adobe makes a standard and premium version of their suites. The have different features. For example STD has Photoshop STD and Premium has Photoshop Extended. You pay more because it has more features. Also sticking with that Adobe Suites of the past may have only required 256MB - 512MB of Ram, so now that they require 1GB - 2GB of Ram aren't they telling you what kind of hardware you can run their products on? I think so. Your little comment about HDD limits was a bit immature. Past versions of Windows had a limit but as that evolved the limits were raised. This is no different really. If you are a home user like the Windows Version is marketed towards then you get the home version. If you are a professional user (or think you are a professional user) get the pro version. Besides name me one home application or any game that can address that much memory even when multi-tasking. Most applications today that I have see that a home based computer will run do not address more than 2GB of ram individually. So really the 16GB limit is not really affecting anyone. So if you are Sally Student or Mommy or Granny at home what could they possibly run that will use that much ram in the foreseeable future? Not to mention what home based PC manufacturer is going to build a computer that can even accommodate that much RAM. If an OEM is going to let you build a system with 16+GB of Ram they will probably flag it that you need Windows Pro and if you are into building your own systems and consider yourself a power user then use Windows Pro if you want Windows. Or just use an alternative OS like one of the many *nix flavors so that you can be like other Linux Fanboys and come here and say how much better your OS is. I mean if you can afford to drop $400 of Ram into your computer (based off average DDR3 memory prices) or probably more if you buy a computer from an OEM then whats the big deal. If you don't like it then don't buy it but quite coming here and saying the MS is trying to run your life. You sound like a spoiled teenager yelling at their parents.

One last thing about your last paragraph. You said and I quote "If you want your
printer to work you need to buy Ultimate". I think you have this confused and a bit backwards. It should read if you want to use Linux or a Mac you need to select from these limited choices of hardware. Sound like they are limiting too huh?
0 Votes
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I realize you're being facetious... But..
Wolfie2K3 29th Apr 2009
There ARE actually limits to how big a hard drive's partition can be in Windows. Current versions of NTFS can support a maximum of 2e64 (that's 2 to the 64th, or over 17 BILLION Gigabytes.)... Good luck finding a drive today that big.

Previous versions of NTFS only supported drives smaller than 137 GB. When the time came, and drives were pushing that limit, Microsoft wrote new code to take advantage of the larger sizes. And guess how much they charged for the update?

That's right - ZIP. Zilch. ZERO. Nada. Nothing.
0 Votes
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I believe that was a limit of ATA and not NTFS.
ye Updated - 29th Apr 2009
The 128GB limit was due to the 28 bit addressing in the original ATA specification (2^28 * 512 = 128GB. The latest specification uses a 48 bit address for significantly greater capacity.
0 Votes
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PageTable is the culprit
thandermax 8th Jun 2010
Limitation of MAX memory size depends on many factor,
first and foremost problem will be sheer level of Pagetable and it's size.

In case of 64bit memory for 4KB(2^12) page, no of entry will be 2^52. which is huge.

For 64 bit memory, pagetable will be splitted up into multiple level, without that to address 2TB memory , your page table will consume considerable amount of RAM.

Also any look up into that HUGE table will be slow.

CPU incorporates TLB (which is a cache memory of recently/frequently used page table entry), but 64 bit still a daunting challenge .

One way of reducing that table size will be using large page (4MB ?) .

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