[SOLVED] Wrong RAM memory information at BIOS and Linux

felipefv · 11-04-2010, 08:27 PM

Hi,

I have 4GB RAM installed on my PC (ASUS P7H55M-BR, Intel i3 530 2,93Ghz). Onboard video has 32 MB (BIOS config).

It should be this way (or maybe not?):

Each slot has 1GB of RAM memory: 4 x 1024 MB = 4096 MB.
Now, subtracting the video memory: 4096 MB - 32 MB = 4064 MB.
It's working on Dual Channel.

But when I am booting the system, the BIOS shows only 3920 MB (3,9GB). Linux shows even lower: 3881 MB.

Memory Remap Feature is enabled at the BIOS config.

Any suggestions about what is happening here?

Thanks!

mf93 · 11-04-2010, 08:49 PM

32 bit operating systems can only 'see' 4.0 GB of ram because of memory address length restrictions (a memory address is 4 bytes long, or 32 bits, so you can have 2^32 addresses or 4GB of addresses). However, much of the memory is taken up by memory-mapped i/o, usb ports, etc. to the point that much of it is taken up. In windows you lose about .8GB ram but with linux you will only lose about 100MBs. Just another reason to switch to linux. XD

kbp · 11-04-2010, 08:51 PM

Maybe you have other memory mapped devices ... ?

felipefv · 11-04-2010, 08:55 PM

mf93,

Sorry, I forgot to say that I'm posting this on WinXP, but I use Debian Squeeze 64bits (amd64).

kbp,

Can you give me some examples of devices that could use the memory?

mf93 · 11-04-2010, 08:58 PM

ROM video memory, devices that need to communicate with the CPU like a keyboard, chips on the motherboard, the list goes on and on...So anyway point is this is natural and you shouldnt worry about it.

felipefv · 11-04-2010, 09:02 PM

mf93 and kbp,

Thanks for the help!

Solved =)