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#1 2011-02-09 19:50:18

macross
Member
Registered: 2009-11-16
Posts: 21

Ram issue

So my computer has 4 gigs of ram, I have installed arch linux 64bit version, but when i look at total memory in linux it only says 3.5gb what gives :S?

Last edited by macross (2011-02-09 19:55:51)

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#2 2011-02-09 20:30:56

stqn
Member
Registered: 2010-03-19
Posts: 1,191
Website

Re: Ram issue

Do you have an integrated GPU? It could be that 512MB are allocated to it.

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#3 2011-02-09 20:47:07

karol
Archivist
Registered: 2009-05-06
Posts: 25,440

Re: Ram issue

stqn wrote:

Do you have an integrated GPU? It could be that 512MB are allocated to it.

+1

If it's not the case, post the command you used to check the amount of RAM and the output, e.g.

[karol@black ~]$ free -m
             total       used       free     shared    buffers     cached
Mem:           490        478         12          0          9        287
-/+ buffers/cache:        181        309
Swap:          258          0        258

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#4 2011-02-09 21:34:55

macross
Member
Registered: 2009-11-16
Posts: 21

Re: Ram issue

karol wrote:
stqn wrote:

Do you have an integrated GPU? It could be that 512MB are allocated to it.

+1

If it's not the case, post the command you used to check the amount of RAM and the output, e.g.

[karol@black ~]$ free -m
             total       used       free     shared    buffers     cached
Mem:           490        478         12          0          9        287
-/+ buffers/cache:        181        309
Swap:          258          0        258

Yes my gpu is integrated (acer 5742) in manufacturer specifications it says "Intel® HD Graphics with 128 MB of dedicated system memory" so i thought that 128mb of ram would be detected not whole 500mb.

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#5 2011-02-09 21:37:51

karol
Archivist
Registered: 2009-05-06
Posts: 25,440

Re: Ram issue

If your card has dedicated memory it shouldn't "steal" any from your RAM.
Maybe it's a BIOS issue. Have you tried running any other systems on this computer? Do they report whole 4 GB?

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#6 2011-02-10 08:02:38

macross
Member
Registered: 2009-11-16
Posts: 21

Re: Ram issue

Laptop came with no OS so i have installed arch. In bios it says that i have 4 gigs of ram. Don't want to install windows but i guess i must in order to check if win reports whole 4gigs...
EDIT: Installed win7 64bit and it reports 3.7GB.

Last edited by macross (2011-02-10 08:44:14)

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#7 2011-02-10 10:04:41

karol
Archivist
Registered: 2009-05-06
Posts: 25,440

Re: Ram issue

macross wrote:

Laptop came with no OS so i have installed arch. In bios it says that i have 4 gigs of ram. Don't want to install windows but i guess i must in order to check if win reports whole 4gigs...
EDIT: Installed win7 64bit and it reports 3.7GB.

You can pick a live distro to double-check, but http://superuser.com/questions/118832/3 … dows-7-x64 and http://support.microsoft.com/kb/929605 say it's the hardware configuration

Microsoft Support wrote:

For example, if you have a video card that has 256 MB of onboard memory, that memory must be mapped within the first 4 GB of address space. If 4 GB of system memory is already installed, part of that address space must be reserved by the graphics memory mapping. Graphics memory mapping overwrites a part of the system memory. These conditions reduce the total amount of system memory that is available to the operating system.

Microsoft Support wrote:

The BIOS must support the memory remapping feature. The memory remapping feature allows for the segment of system memory that was previously overwritten by the Peripheral Component Interconnect (PCI) configuration space to be remapped above the 4 GB address line.

Microsoft Support wrote:

Note When the physical RAM that is installed on a computer equals the address space that is supported by the chipset, the total system memory that is available to the operating system is always less than the physical RAM that is installed. For example, consider a computer that has an Intel 975X chipset that supports 8 GB of address space. If you install 8 GB of RAM, the system memory that is available to the operating system will be reduced by the PCI configuration requirements. In this scenario, PCI configuration requirements reduce the memory that is available to the operating system by an amount that is between approximately 200 MB and approximately 1 GB. The reduction depends on the configuration.

Last edited by karol (2011-02-10 10:10:22)

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#8 2011-02-10 18:20:28

macross
Member
Registered: 2009-11-16
Posts: 21

Re: Ram issue

karol wrote:
macross wrote:

Laptop came with no OS so i have installed arch. In bios it says that i have 4 gigs of ram. Don't want to install windows but i guess i must in order to check if win reports whole 4gigs...
EDIT: Installed win7 64bit and it reports 3.7GB.

You can pick a live distro to double-check, but http://superuser.com/questions/118832/3 … dows-7-x64 and http://support.microsoft.com/kb/929605 say it's the hardware configuration

Microsoft Support wrote:

For example, if you have a video card that has 256 MB of onboard memory, that memory must be mapped within the first 4 GB of address space. If 4 GB of system memory is already installed, part of that address space must be reserved by the graphics memory mapping. Graphics memory mapping overwrites a part of the system memory. These conditions reduce the total amount of system memory that is available to the operating system.

Microsoft Support wrote:

The BIOS must support the memory remapping feature. The memory remapping feature allows for the segment of system memory that was previously overwritten by the Peripheral Component Interconnect (PCI) configuration space to be remapped above the 4 GB address line.

Microsoft Support wrote:

Note When the physical RAM that is installed on a computer equals the address space that is supported by the chipset, the total system memory that is available to the operating system is always less than the physical RAM that is installed. For example, consider a computer that has an Intel 975X chipset that supports 8 GB of address space. If you install 8 GB of RAM, the system memory that is available to the operating system will be reduced by the PCI configuration requirements. In this scenario, PCI configuration requirements reduce the memory that is available to the operating system by an amount that is between approximately 200 MB and approximately 1 GB. The reduction depends on the configuration.

Well that made things clear. Thanks.

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