In article news: said:
That's the bit I'm unsure about. The web page describes a maximum of
4GB of real memory and 2GB of virtual memory, plus presumably up to 1GB
for the latest graphics cards and a bit more for the other
memory-mapped peripherals.
The physical memory limit of 4GB depends on the OS code and on the
processor/chipset architecture. Most motherboards for 32-but chips won't
support more than 4GB total memory addressable by the CPU.
Graphics chipsets that use the main PC memory will effectively reduce the
memory available by using some of that <4GB RAM. Memory on graphics cards
that have their own RAM does not count against this limit because it is not
mapped into the CPU's memory addressing space (or not all at once, anyway,
so the effect is small).
Is all that additive, making a theoretical maximum of about 7.1GB in
Windows 2000 Professional, or does the addressable real and virtual
memory get cut back, to keep the total address space down to 4GB?
No, it's not additive. Standard Win2k Workstation allows 4GB of physical
memory. The 32-bit CPU has a 4GB address space, of which the OS makes half
(2GB) available for user processes and keeps the other half for the OS. The
addressing is virtual so each user process gets a separate 2GB address
space, but not its own 2GB of physical RAM.
4GB is the physical limit of most systems, but (as that Microsoft article
explains) the PAE (Physical Address Extension) capabilities of Pentium Pro
and later CPUs makes it possible to provide up to 36-bits (64GB) of
physical memory addressing. PAE requires chipset support which is only
normally found on server motherboards ... most workstation chipsets don't
support PAE and limit you to 4GB -- indeed, many 32-bit motherboards that
are capable of holding up to 4GB of RAM make significantly less available
because part of the addressing space of the chip is required for other
purposes.
It would help to know what your motherboard is ...?
In any case, there should be no problem using 3GB with Win2k ... it's just
that 4GB may but you less than you think (depending on how your
motherboard/chipset copes with it) and you can't use more than 4GB without
a server motherboard.
At the moment, I'm using it for transcoding MPEG-2 files to MPEG-4,
using two instances of a program called AutoGKnot on a dual core Athlon
64.
Ah, that's different. The physical limits are different on 64-bit systems
because the CPU has a greater addressing range (note that PAE isn't
supported on 64-bit chipsets because it isn't needed) -- as long as you are
running a 64-bit OS. I don't know whether a 32-bit OS can take advantage of
the greater addressing range of 64-bit CPUs in the same way that server
versions of Windows use PAE.
