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Anyone have 4 gigs in 32 bit XP/Vista?

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January 10, 2009 3:02:04 AM

I read through the memory faq and need a more specific explanation here.

Specs:
Intel 975x (supports 8 gigs DDR2 800)
E6600
4 gigs DDR2 800
ATI 4870 (512MB)


I just installed 2 more gigs of DDR2 800 to bring me up to 4. Of course it is only being read at 3.25 gigs by my system, but it still is noticeably faster. Where opening programs were once hesitant with 2 it is near-instant since doubling it.

I've read though about how any "missing" RAM is being "wasted", in my case about 750 MB or so, but isn't it still being "used" for MMIO functions, such as the video card and bios?

Why aren't these MMIO functions using any memory when running 2 gigs or less?

My total physical memory is showing roughly 3.4 gigs (available is a bit over 2.8 gigs), whereas total kernel is a bit over 106 megs. I've read that it should be more for stability purposes but so far it seems to be running well. Would it be a good idea to check the /MAXMEM= box in the boot.ini tab and set it to 2048?

Any ideas or info is much appreciated.

More about : gigs bit vista

Anonymous
a b } Memory
January 10, 2009 9:47:22 AM

how come my ram shows up as 4gig under vista 32
January 10, 2009 3:29:32 PM

Your mmio isn't using memory it's using part of the cpu. when running 32 bit it only support 4 gb total so even though you have 4 gb of memory only about 3.1 gb of it is being used because the cpu needs the other .9 gb of space for mmio. look for a memory remap feature in you bios or get a 64 bit operating system if your cpu supports it.(not recommended unless your willing to pay for it and look for 64 bit versions of all your drivers and programs.


cainey,
Vista, due to requests from hardware vendors shows the total amount of ram installed and not how much is used because they would rather cover up the problem than provide you with 64 bit or give you 3gb instead of 4
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January 10, 2009 3:54:47 PM

IBM when they invented first PC in the 80's they couldn't predict that 4 gigs of RAM would be a common thing today there first PC used 4.77 mHZ CPU from intel and total of 16 kilobytes of ram :> and part of RAM is adressed to hardware and cant be used by the operation system and any application
it is used for adresses of hardware IRQ'S and many more other stuff.
So back then they set like a baseline of 4gigs of RAM and from it 500 mb or more should be saved for "Adreses" that your hardware uses.
January 10, 2009 3:57:51 PM

reffu said:
Your mmio isn't using memory it's using part of the cpu. when running 32 bit it only support 4 gb total so even though you have 4 gb of memory only about 3.1 gb of it is being used because the cpu needs the other .9 gb of space for mmio. look for a memory remap feature in you bios or get a 64 bit operating system if your cpu supports it.(not recommended unless your willing to pay for it and look for 64 bit versions of all your drivers and programs.



mdma35 said:
IBM when they invented first PC in the 80's they couldn't predict that 4 gigs of RAM would be a common thing today there first PC used 4.77 mHZ CPU from intel and total of 16 kilobytes of ram :> and part of RAM is adressed to hardware and cant be used by the operation system and any application
it is used for adresses of hardware IRQ'S and many more other stuff.
So back then they set like a baseline of 4gigs of RAM and from it 500 mb or more should be saved for "Adreses" that your hardware uses.




Ahhh I see. What doesn't make sense to me though is why it's only shown as missing when you have 4 gigs. Isn't the hardware still doing the same thing no matter how much RAM is installed? For instance if I have 2 gigs why isn't it showing as 1.1 because of MMIO functions? Or is it just a flaw detecting memory addresses past 3 gigs, and all the memory is still being used the same way?
a b } Memory
January 10, 2009 4:17:05 PM

Analogy:
There is a cup that holds 1 gallon of water. Think of the MMIO as a rock sitting at the bottom (displacing water). If you pour in half a gallon of water, the cup doesn't overflow. When you pour in a gallon of water to the cup, it will overflow (the rock takes up space) and you can't really hold a gallon of water.

It's early in the day, hope that makes sense ;) 
January 10, 2009 7:26:01 PM

festerovic said:
Analogy:
There is a cup that holds 1 gallon of water. Think of the MMIO as a rock sitting at the bottom (displacing water). If you pour in half a gallon of water, the cup doesn't overflow. When you pour in a gallon of water to the cup, it will overflow (the rock takes up space) and you can't really hold a gallon of water.

It's early in the day, hope that makes sense ;) 



So in essence the MMIO is first and foremost taking up a predetermined amount of memory address space, but does it also have anything to do with the difference between total physical memory and available, ie pulling from the total whatever is needed, or is that all OS applications, including for the video card driver? I notice pretty much the same difference between the two with either 2 gigs installed or 4.
a b } Memory
January 11, 2009 3:16:43 PM

Total physical and total available have nothing to do with address space (primarily). They have to do with the processes running at any given time. MMIO doesn't actually take any resources other than address space.

January 11, 2009 4:38:49 PM

festerovic said:
Total physical and total available have nothing to do with address space (primarily). They have to do with the processes running at any given time. MMIO doesn't actually take any resources other than address space.


So the graphics card along with MMIO, buffers, BIOS etc. don't use any of the total physical RAM, (unless say the graphics card doesn't have its own on board memory), and only use up x amount of memory address space, correct?

I totaled up all the processes I have running and the memory they take up is still about 240 MB shy of (total RAM - available RAM). What could that amount be tied to?
January 12, 2009 1:21:21 AM

festerovic said:
Part 1: Correct.

Part 2: I don't really know. Read this, see if it answers more thoroughly than what we've discussed.
http://en.wikipedia.org/wiki/MMIO



Thanks for the help!
January 12, 2009 6:08:21 AM

mdma35 said:
IBM when they invented first PC in the 80's


If you talk about cpus, it is not a problem. 32bit cpus have been able to address much more than 4GB for years. xp and vista are software-limited to 4GB
!