4GB RAM???

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Guest

I have a brand new pc with Vista Pro and 4Gb of RAM DDR800 on board. BIOS
correctly recognizes the right amount of memory but Windows don't. It reports
only 3,5 RAM. Am I missing something or it's a O.S. limit?
Thanks in advance.

Michelangelo Togni
 
It is a 32 Bit limit, regardless of the OS. If you have a 64 bit processor,
you can install the 64 bit version of Vista and it will "see" all of the
RAM.

The 4 GB is there, but due to the 32 bit memory addressing limit, the OS
only see's ~3-3.5 GB. The other addressing space is for the video card, BIOS
and other hardware.
 
So the remaining 0.5 Gb is not lost but is used by the system? If so I think
this is not so bad, however "something" use it...
 
AFAIK it is not actually used by the system. The addresses are reserved for
use by other cards such as a graphics card with 512 MB of on board memory to
addressee their own memory so the OS itself can not use the space.
 
Cal,

3.5 GB is the limit of 32-bit OS. My computer claims to take 4 GB RAM so it
is not much useful to add up to the max. as I have 2 GB RAM on my computer.
Other parts of computer will use the RAM over 3.5 GB. Is it really true on
every Vista computer or subject to certain conditions as my video card is
independent one, not share the system RAM?

Thanks,

Scott
 
It isn't the physical RAM that is the problem. It is the addressing system.
Basically, the system maps everything it needs to a (hate to use the word,
as it's not really accurate) virtual memory place, or address space. This
place can only be 4 GB in size. This includes the RAM, video card, BIOS, and
other hardware that maps itself there. If you have an independant video
card, that will reduce it by the amount of RAM the card has.

Imagine a map of a factory 4 acres in size. You have 4 acres of product
(RAM), but the shelves, equipment and boxes (video card, BIOS, etc.). The
factory can support 4 acres of total space, but only a certain amount is
available for certain things. There is going to be some overhead.

--
Dustin Harper
(e-mail address removed)
http://www.vistarip.com

--
 
http://support.microsoft.com/kb/929580

A 32-bit operating system can address memory that is relocated above the 4
GB boundary if the following conditions are true:
• The computer is in Physical Address Extension (PAE) mode.
• The computer has 4 GB of RAM.
In this case, the operating system correctly reports how much memory is
installed.

To enable PAE mode, you have to add PAE to the boot entry in the BCD file.
Open an elevated command prompt. Type BCDEDIT /SET PAE ForceEnable.

I did this and checked to see if pae was set to forceEnable but typing
bcdedit, but it didnt work. any suggestions? why
 
JW said:
You did not understand the KB article a 32 bit OS can not address memory
over 4GB period.
Click to expand...

It depends on how the OS implements PAE. PAE allows for more than 32 bit
of physical memory to be addressed
 
jorgen said:
It depends on how the OS implements PAE. PAE allows for more than 32 bit
of physical memory to be addressed
Click to expand...

It also depends on if the motherboard allows it.

Tom Lake
 
For some reason Windows Vista on my PC is only reading 2558 MBs of ram of the
4GBs that I have installed and the BIOS reads. It is a 32 bit copy and I
know video cards like to use the system memory, but is that possibly what is
going on here? Seems to be a little much missing.
 
The sad but true facts:

*You need a x64 processor,
*x64 motherboard with RAM remapping support (anything new or AM2 compatible)
*x64 motherboard must support, not have, 8GB of RAM, but can have 8GB if you
wish,
*x64 vista OS.

Most cases you just need to move up to the x64 OS, this gives you more
performance than a 32bit OS, i personaly gained an extra 294 3D benchmark
points from the switch. Your also pretty much assured to meet the above
requirments if your system is new, but some older systems may work, don't
forget to backup OS BEFORE updating, as to evade any errors or no gos. If you
have the original version of windows XP (no service packs) and the upgrade
pack of vista you can do a full clean install of vista 64bit (if you have
ulitmate).
 
How many video cards do you have and with how much ram? That will acount for
some of the reduction.
 
This is in fact, very sad. You need a motherboard that supports up to 8GB.
My motherboard is expandable up to 4 gigs. The BIOs reads 4 full GBs of
RAM, But the 64bit OS only reports 3.25gb. I was runnning the 64bit OS with
3 gigs of RAM (2 gigs, 2 512s) and it reported the full 3 gigs. Junk.
 
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