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You are here: MacNN Forums > Software - Troubleshooting and Discussion > Alternative Operating Systems > 4GB RAM showing as 2.96

4GB RAM showing as 2.96
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OnTheKeys
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Sep 16, 2008, 12:25 PM
 
in My Computer and 3036MB in System properties...I have 4GB installed, anyway to get this RAM back?
     
Tomchu
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Sep 16, 2008, 12:49 PM
 
First of all, I'll state the obvious and say that you're probably on the wrong forum if you're looking for help with your PC/Windows, but ...

Read this article: http://www.appleinsider.com/articles...c_swindle.html (specifically the "Virtual Memory, PAE, and the 4GB barrier" and "System RAM vs MMIO: the 'where is my 4GB?' problem" sections). It will answer all of your questions.

If you just want the quick-and-dirty answer, it's because you're running a 32-bit operating system, and it needs to use some of that 4 GB address space for addressing devices. Upgrade to a 64-bit OS if you want to be able to use all 4 GB.
     
OnTheKeys  (op)
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Sep 16, 2008, 04:55 PM
 
Well i'm on a macbook that's why i'm here. Using Bootcamp, i'm not sure that I can upgrade to a 64 bit system, because that depends on the processor, correct? My macbook has the Intel Core 2 Duo 2.2 GHz.
     
Tomchu
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Sep 16, 2008, 06:05 PM
 
Fair enough. :-P

The Core 2 Duo is 64-bit capable. I'm not sure about the chipset in your MacBook. Others here know more about the chipset history of MacBooks and which ones are 64-bit capable.

I suppose one easy way of figuring it out would be to download and burn a live CD of some 64-bit Linux distribution, and then attempt to boot it up. If it works, 64-bit XP ought to work too.

However, do you really need all 4 GB in Windows? If not, save your time. Not everything is supported in 64-bit XP.
     
OnTheKeys  (op)
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Sep 16, 2008, 08:26 PM
 
I score films and video games using Virtual Orchestras, I need every byte of RAM I can get
     
mduell
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Sep 17, 2008, 04:43 PM
 
If your Mac supports 4GB RAM, it's 64-bit capable. All the 32-bit Intel Macs were crippled to 2GB RAM.
     
Tomchu
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Sep 17, 2008, 09:34 PM
 
mduell, what do you mean by "supports"? Everything from a late 2006 MacBook and on will take 4 GB, but not all of those models will be able to use all 4 GB.

I suppose a better way of saying it would be "If OS X lets you use all 4 GB, it's 64-bit capable".
     
OnTheKeys  (op)
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Sep 17, 2008, 10:03 PM
 
Well OSX shows 4GB in "About this Mac" and Vista shows 2.96. So I can run a 64 bit OS?
     
TheoCryst
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Sep 18, 2008, 12:37 AM
 
Originally Posted by OnTheKeys View Post
Well OSX shows 4GB in "About this Mac" and Vista shows 2.96. So I can run a 64 bit OS?
Yep. The Core 2 Duo processor in your MacBook is 64-bit capable, and the fact that OS X recognizes all four confirms this. Vista 64-bit should run just fine for you.

Any ramblings are entirely my own, and do not represent those of my employers, coworkers, friends, or species
     
Sherman Homan
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Sep 18, 2008, 06:30 AM
 
Originally Posted by OnTheKeys View Post
Well OSX shows 4GB in "About this Mac" and Vista shows 2.96. So I can run a 64 bit OS?
There is your answer, your Mac is fine, it is your Windows OS that is crippled. You need the 64 bit version of XP or Vista.
[edit, sorry TheoCryst, I missed your post, you nailed it.]
     
hwojtek
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Sep 18, 2008, 09:49 AM
 
Originally Posted by Tomchu View Post
I suppose a better way of saying it would be "If OS X lets you use all 4 GB, it's 64-bit capable".
Nope.
"If OS X lets you use all 4 GB, your chipset supports 64-bit computing properly."

It's a well-documented fact that while you can physically put 4 GB into a Macbook or a Mac Mini, only 3 GB will be used (despite the fact "About this Mac" box says 4 GB installed). A quick sum of all used and free memory using Activity Monitor clears all doubts about it.
Wojtek

All Macs still running: iMac G3 Trayloader 333MHz, iMac G3 350 MHz, iMac G4, PM G4 DP 1.6 GHz, 2 x eMac 1 GHz, PBG4 12" 1.5 GHz, Mac SuperMini™ C2D 2.33GHz/802.11n/200GB, Mac Pro Quad Core 2.0 GHz/4GB.
     
Cadaver
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Sep 18, 2008, 12:18 PM
 
Originally Posted by hwojtek View Post
Nope.
"If OS X lets you use all 4 GB, your chipset supports 64-bit computing properly."

It's a well-documented fact that while you can physically put 4 GB into a Macbook or a Mac Mini, only 3 GB will be used (despite the fact "About this Mac" box says 4 GB installed). A quick sum of all used and free memory using Activity Monitor clears all doubts about it.
Not quite true. Depends on the machine.

- Core Duo MacBooks will support a maximum of 2GB RAM. May not boot if you put more in.
- Core 2 Duo MacBooks with GMA 950 graphics will support a maximum of 3GB of RAM, even if you put 4GB in.
- Core 2 Duo MacBooks with X3100 graphics will support 4GB of RAM.

The Core Duo Mac minis are limited to 2GB. The Core 2 Duo Mac minis will accept 3GB; you can put 4 in, but it wont see all of it (MacOS or Windows). Since there is no Santa Rosa chipset version of the Mac mini - unlike the MacBook - you can't access 4GB of RAM.

32-bit Windows operating systems (XP and Vista), regardless of the hardware you run it on (Apple, HP, Dell, etc.) will address at most a bit over 3GB of RAM, regardless of how much is installed on the machine. I've got 6GB of RAM in my Mac Pro, but 32-bit Windows won't use but 3GB of it max.

Vista SP1 will report 4GB in your machine if its physically installed, but the top 0.8GB is still unusable - regardless of chipset or processor. This is due to the way 32-bit Windows handles its hardware addressing. Its a hard-coded limit. BTW, pre-SP1 Vista reports 3GB.

Vista 64-bit versions will support 4GB or more of RAM, however you must make sure that your applications will run properly on Vista x64. Not all apps and device drivers will run properly, and even if they do they may not be able to take advantage of all the RAM in the machine if they're not coded for it. For example, Adobe Creative Suite 3 will run on Vista x64, but the apps themselves are still limited to (I believe) 2GB per application. The new CS4 for Windows however is specifically coded to take advantage of all the RAM space when used with 64-bit Windows.
     
mduell
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Sep 18, 2008, 12:55 PM
 
Originally Posted by Tomchu View Post
mduell, what do you mean by "supports"? Everything from a late 2006 MacBook and on will take 4 GB, but not all of those models will be able to use all 4 GB.

I suppose a better way of saying it would be "If OS X lets you use all 4 GB, it's 64-bit capable".
By "supports" I mean "doesn't turn into a turnip when you install 4GB." That includes all Core 2 Duo Macs.
The 3.mumble GB hardware addressing issue is entirely independent of what OSs your Mac can run.
     
   
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