Nico said:
Thanks Paul, that's what I did. There must be more to it, because even
when I reinserted the original RAM, I still had 750 MB :-(
/Nico
You can use CPU-Z, to get some basic information about memory
in the computer. But this does not help with the problem you are having.
This is still a useful utility though, and I keep a copy
on all the computers.
(No-install version of CPU-Z)
http://www.cpuid.com/downloads/cpu-z/1.71-en.zip
*******
This test, tells you how much memory it finds.
It is an *independent* verification of BIOS-detected RAM.
Windows OS cannot screw this up.
http://www.memtest.org/
Scroll half way down the page, to the download section.
Memtest86+ makes "boot media" and there is no OS running
while you use memtest86+. The program tells you how much
memory is present. And in this case, that is the function
you are interested in.
It is still possible for the BIOS to "reserve" memory,
and memtest86+ actually responds to the reservation
information in an appropriate way. Otherwise, the
computer could crash.
*******
You should check in the BIOS, that the onboard graphics
have not been allocated too much memory. There is a
static allocation and a dynamic allocation, and the
BIOS may have a static allocation listed. For a modern
OS, 128MB is sufficient for testing purposes (so that
Aero or Compiz can run).
*******
In Windows, there is an item you can add to boot.ini, to
eliminate some of the memory.
It's possible the entire 4GB is actually being detected. But
it is causing a problem. Setting /MAXMEM to slightly less
than 4GB, might help in such a case.
If you have a Linux LiveCD, you could try testing from an
alternate OS. And use "top" or "vmstat" to collect some
information. There are probably other places in the file
system, with physical memory information (/sys ? /proc ?
I'd have to go look that up).
In Windows 98, there was a separate file where you could
limit the system file cache, and limit the maxmem for
the OS. I used that, so that Win98SE could be instructed
to use only 512MB of the 2GB available inside my computer.
Once maxmem is set, the OS really thinks the computer
only has 512MB.
So the Windows OSes do have a means to "hide" available memory.
And by using the BIOS, and allocating static memory to the
onboard graphics frame buffer, it is possible to lose some
of the memory there. Perhaps that will become more clear
when you run memtest86+.
So at the very least, you should enter the BIOS setup, and
see if the graphics setting is mis-adjusted. The BIOS will
also display a message during startup (when the first page of
POST text appears), where it displays the amount of memory detected.
If the BIOS text is not visible, enter the BIOS and
disable "full screen logo" in the BIOS. That is one
of the first things I disable in the BIOS, so the
POST text is always available.
Here, before graphics allocation, the BIOS has detected 4096MB.
http://wincustomizing.client.jp/img/bios/post1.jpg
*******
As for the BIOS, it uses two methods to detect memory. On
the one hand, it reads the SPD serial EEPROM on each DIMM,
and gets "2GB" value on your SODIMMs. But, the BIOS does
not "trust" this reading. The BIOS uses the legacy "peek
and poke" method, where the BIOS writes to memory addresses
and then reads them back. This is one reason the BIOS hardly
ever crashes, even when the contents of the SPD serial chip
are incorrect. One poster bought a RAM, where the SPD chip
soldered to the DIMM, was the wrong one. The SPD said the
DIMM was twice as big as it actually was - but because the
BIOS uses the legacy test method of peek and poke, both the
BIOS and the OS survived, and the true amount of memory
was evident at both levels.
Paul
