Which Windows detects 4GB+ RAM?

JohnJSal

JohnJSal

Active Member
First off, what I know is that 32-bit XP can't detect more than 4GB. Can it detect 4, or is it just 3GB?

What I don't know is if 32-bit Vista can detect 3/4GB+, or is there even a 32-bit Vista at all?

Just trying to figure out the "rules" for how much RAM is detected under what version of which OS. :rolleyes:
 
Generally you will see anywhere from 2.5-3.2GB of RAM when you have 4GB of RAM installed, it depends on how much memory is allocated to all the other components in your system. And yes they do make 32 bit versions of Vista.
 
[-0MEGA-];925490 said:
Generally you will see anywhere from 2.5-3.2GB of RAM when you have 4GB of RAM installed, it depends on how much memory is allocated to all the other components in your system. And yes they do make 32 bit versions of Vista.
Click to expand...

What do you mean by how much memory is allocated to other components?

And for 64-bit versions, you'll see whatever the full amount is?
 
Yes all 32 bit vista's can detect about 3-3.5gb of ram and thats it. 64bit vista's can detect 16gb of ram but that is way more than you would need anyway.
 
g25racer said:
Yes all 32 bit vista's can detect about 3-3.5gb of ram and thats it. 64bit vista's can detect 16gb of ram but that is way more than you would need anyway.
Click to expand...
They can detect up to 128GB.

What do you mean by how much memory is allocated to other components?

And for 64-bit versions, you'll see whatever the full amount is?
Click to expand...
The main component is the video card, as that would basically be subtracted from the 4GB, as well as any other components that require mapped memory.

A 64 bit OS can see up to 128GB, however I'm sure theres a similar issue where it may only see 127GB or something.
 
[-0MEGA-];925517 said:
The main component is the video card, as that would basically be subtracted from the 4GB, as well as any other components that require mapped memory.
Click to expand...

But if you have a dedicated video card, why would you see less than your actual amount of RAM?
 
It's the way Vista maps out it's memory

Taken from Microsoft site
For example, if you have a video card that has 256 MB of onboard memory, that memory must be mapped within the first 4 GB of address space. If 4 GB of system memory is already installed, part of that address space must be reserved by the graphics memory mapping. Graphics memory mapping overwrites a part of the system memory. These conditions reduce the total amount of system memory that is available to the operating system.

The reduction in available system memory depends on the devices that are installed in the computer. However, to avoid potential driver compatibility issues, the 32-bit versions of Windows Vista limit the total available memory to 3.12 GB. See the "More information" section for information about potential driver compatibility issues.

If a computer has many installed devices, the available memory may be reduced to 3 GB or less. However, the maximum memory available in 32-bit versions of Windows Vista is typically 3.12 GB.
 
TFT said:
It's the way Vista maps out it's memory

Taken from Microsoft site
For example, if you have a video card that has 256 MB of onboard memory, that memory must be mapped within the first 4 GB of address space. If 4 GB of system memory is already installed, part of that address space must be reserved by the graphics memory mapping. Graphics memory mapping overwrites a part of the system memory. These conditions reduce the total amount of system memory that is available to the operating system.

The reduction in available system memory depends on the devices that are installed in the computer. However, to avoid potential driver compatibility issues, the 32-bit versions of Windows Vista limit the total available memory to 3.12 GB. See the "More information" section for information about potential driver compatibility issues.

If a computer has many installed devices, the available memory may be reduced to 3 GB or less. However, the maximum memory available in 32-bit versions of Windows Vista is typically 3.12 GB.
Click to expand...

Yikes, sounds inefficient. :)
 
TFT said:
For example, if you have a video card that has 256 MB of onboard memory, that memory must be mapped within the first 4 GB of address space. If 4 GB of system memory is already installed, part of that address space must be reserved by the graphics memory mapping. Graphics memory mapping overwrites a part of the system memory.
Click to expand...

This might reveal some ignorance on my part, but couldn't it be designed so that the installed RAM doesn't occupy the first 1 or 2GB of address space, so there won't be any overlap between it and the memory required by other components?

Or similarly, why can't other components be mapped to the space after the first 4GB?

Or something.......
 
It is a hardware design.

Most modern computers can remap memory, so there won't be a conflict, but Microsoft doesn't want to support more than 4 GB in total in their 32-bit desktop editions
 
It doesn't matter if it's Windows or any other OS. All 32-bit operating systems mathematically can only address 4gb of memory. I thought 64-bit sees double that, but some systems like Servers can see more through their hardware architecture. I'm running 32-bit Windows Vista Ultimate with 2gb memory right now. Most tests I've read say that is a sweet spot and you rarely need more than that. But I do plan to max out my system board to 4gb in the near future. Then I'll see how much free memory I have after everything loads up. But I do have a dedicated graphics card (with 768mb) and sound card so they should help to get me somewhat over the 3gb hump.
 
Steve Mavronis said:
It doesn't matter if it's Windows or any other OS. All 32-bit operating systems mathematically can only address 4gb of memory.
Click to expand...

No, because of how it works when going from virtual to physical addresses, you can easily go beyond 4 GB in 32-bit OSes. Since many years ago, all x86 processors have been able to address 64 GB in PAE mode.
 
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