Official Memory Size for 32Bit OS = 3,120MB Vista News Discuss Official Memory Size for 32Bit OS = 3,120MB in the Windows Vista forums; 64-bit Windows Vista Is Not Enough to Address 4 GB of RAM Windows Vista No Comments »Microsoft’s latest operating system comes in both 32-bit and 64-bit ...

[Snuffy]

64-bit Windows Vista Is Not Enough to Address 4 GB of RAM
Windows Vista No Comments »Microsoft’s latest operating system comes in both 32-bit and 64-bit flavors, but all the editions of Windows Vista have problems using a full 4 GB of RAM. Unlike Apple, which controls the entire hardware and software ecosystem, Microsoft doesn’t have the luxury of scraping support for 32-bit platforms. This is why Vista brings to the table 32-bit and 64-bit editions, an aspect that will remain valid even for its successor, Windows 7 (Seven), currently planned for 2010. One of the main benefits of x64 operating systems, including Vista, is the fact that the platforms support well in excess of 4 GB of system memory. Generally speaking, 32-bit Windows Vista are limited to addressing 3,120 megabytes (MB) of random-access memory. -- SNIP-- • 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. This feature must be enabled in the BIOS configuration utility on the computer. View your computer product documentation for instructions that explain how to enable this feature. Many consumer-oriented computers may not support the memory remapping feature.




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[gilesm]

This is exactly what I found out. I placed 4GB of RAM in my machine, which has an Asus Motherboard and Vista Home Premium (64 bit edition).
When booting I see that the motherboard regsiters 3328 MB of Ram and then quotes another figure in brackets (4GB installed RAM).

So prior to Vista even booting the motherboard can not use all of the RAM.
I wrote to my motherboard supplier and they replied;

"Dear Friend :

Thank you for contacting ASUS Customer Service.

My name is ZYC, and I would be assisting you today.

Not only the OS limit.
The board does not support Memory remap feature,
so after the ram size reach to 4GB, the system chipset will occupy more ram to initialize, the available ram size is less than 4GB, It is about 3GB+.


Thank you for using ASUS products and services! "

So, Asus suggested a new motherboard, supporting memory remap as staed above, which for me would mean a new board, new processor, new RAM (my current is DDR format).

I decided that this was a major cost, and not really worth it at this point.

So I gues I ahve a RAM limit of 3328 meg.
My system is dual boot with XP PRO, and I get the same results if I use Vista or XP. So the OS does not seem to be to balme, this time at least !