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4gb ram installed but only 2.87gb showing in system properties

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platinum gold

platinum gold


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New build just arrived, nice new AMD QUAD PHENOM 9850 with 4 gb ram DDR2 800 (2 x 2g)

Why does it show as just 2.87gb in the system information details?

(I'm using windows XP Pro SP3 32 bit)

The graphics card is ATi Radeon HD2400 Pro and uses the memory/hypermemory on mother board to apparently go upto 1 gig, maybe its stealing some memory from the board and thats why its not showing?

Edited by platinum gold, 26 December 2008 - 12:40 PM.

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A couple quotes that will explain.

All 32-bit versions of Windows (Vista as well as XP), even though
they have a 4GB address space, can only use *around* 3.1GB of RAM.
That's because some of that space is used by hardware and not
available to the operating system and applications. The amount you can
use varies, depending on what hardware you have installed, but is
usually around 3.1GB.

Note that the hardware is using the address *space*, not the actual
RAM itself. The rest of the RAM goes unused because there is no
address space to map it too.

4GB. However, XP does not report the amount of installed ram but the amount
available to user programs. How much will display as available to user
programs varies from around 2.5 to 3.3 depending on the mobo and devices in
the computer. Modern mobos provide for memory mapped I/O and device
designers take advantage of this to enhance performance. However these
memory mapped I/O address spaces are protected from user programs and the
address range is not reported. Hence you don't see 4GB as available. There
is nothing inherent in XP that prevents it from using all 4GB of the 32-bit
address range. It is the BIOS that is reserving some of the space for
hardware buffering and such.

There is no particular reason why XP cannot report installed ram instead of
the amount available in the user space, but the latter is probably more
useful to know and that's how 32-bit Windows has always done it.

However, Vista x86 beginning with SP1 will be reporting the amount of
installed ram so the users who are testing the release candidate right now
are seeing 4GB on the system properties page. This only a change in what is
being reported, however. It does not change what is available to the user.
This change is NOT being retrofitted to XP with SP3.

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I also use "AMD QUAD PHENOM 9850 with 4 gb ram" but my graphics card is a 512 MB nvidia one.

My RAM shows up as 3.25 GB. The reason has already been stated by 123Runner.
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platinum gold

platinum gold


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Ah thats why, thanks, also i wonder if there is an extra 512 meg being used by the hypermemory graphics card, to get it to the advertised 1gb, not sure how i would tell if its doing that but have a 1gb hypermemory radeon ati hd2400 pro graphics card which could be taking 512meg from the board too? The spec of my graphics card is just 256mg http://ati.amd.com/p...0pro/index.html so it has to be taking 256mb from the RAM onboard unless theres a bigger chip than there you would have expected on it.

Edited by platinum gold, 27 December 2008 - 03:47 PM.

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