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Vista 64 Wont Recognize 4 gigs of ram

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June 4, 2008 6:41:03 PM

Hello, I have had the past couple days off of school and work and have taken the time to try and upgrade my system. I've installed two new video cards and an additional two gigs of ram. The problem I am having is that Windows says that I have 4 gigs of physical memory then it says Available physical memory: 2.65 GB. I have been working on fixing this for days and tried some fixes I found in other posts but nothing has completely resolved it. My bios said that all of the memory was not available at first but after turning on the memory hole this fixed that problem (my bios says 4 gigs usable memory). Any help would be greatly appreciated, thank you!

System Specs:

Motherboard: Asus A8n32 Sli Deluxe

Memory: 4 gigs

Video Cards: Gygabyte nvidia 8800 GT x2 SLI

OS: Vista Business 64-bit

a b } Memory
June 4, 2008 6:52:15 PM

System information states you have 4gb of physical memory installed and 2.65 GB is 'still' available. So your system is using or caching 1.35 Gb of the 4 GB available at that time.

On your desktop, right click on the bottom toolbar that runs across the lenght of the screen. Click on Task manager. Select the performance Tab. Memory is showing the amount of system memory being used currently.
June 4, 2008 6:59:36 PM

Thanks Badge, so basically I am just misreading what Windows is telling me? It is saying it is currently using 1.35 Gb out of the 4 Gb available to it? (task managers numbers matches up with what you said)
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a b } Memory
June 4, 2008 7:04:54 PM

Yeah. I have the same ASUS A8N32-SLI Deluxe MB on a system. The amount of RAM the system is using or caching will vary with the tasks you are doing. Vista is very intelligent and proficient at caching the system RAM when compared to old style XP RAM caching.
June 4, 2008 7:08:26 PM

Awesome, thanks for you help!
August 2, 2008 1:55:21 PM

ha was up. i have the same system but it only shows 3.03 GB of total memory. and i have 4 GB put in my system. i tested the ram and slots and both are good and working. so i dont know why 1 GB of my memory is not showing up. do you guys have any idea?
a b } Memory
August 4, 2008 12:44:12 PM

In 32 bit Windows operating systems, the total addressable space available is 4GB. If you install a total of 4GB worth of RAM, the system will detect/use/display less than 4GB of total memory because of address space allocation for other critical functions, such as:

- System BIOS (including motherboard, add-on cards, etc..)
- Motherboards resources
- Memory mapped I/O
- Configuration for AGP/PCI-Ex/PCI
- Other memory allocations for PCI devices

Different onboard devices and different add-on cards (devices) will result of different total memory size. e.g. more PCI cards installed will require more memory resources, resulting of less memory free for other uses.

This limitation applies to most chipsets & Windows XP/Vista 32-bit version operating systems. Again, this is a limitation of the Operating System not having enough address space to allocate to the system *and* the RAM. Not allocating address space to devices renders them inoperable. Not allocating addresses to RAM simply results in the unaddressed section not being used in an otherwise fully functional computer. Therefore the OS designers assign RAM last.

We can have long debates about mathematical fundamentals and discussions about why the original Windows designers couldn't allocate the full theoretical max of 36 bits of address space so that users today would be able to use more resource. But at the end of the day, the designers and engineers 'Didn't Then'. So we 'Can't Now'.


If you install a Windows operating system, and if more than 3GB memory is required for your system, then the below conditions must be met:

1. A memory controller which supports memory swap functionality is used. The latest chipsets like Intel 975X, 955X, Nvidia NF4 SLI Intel Edition, Nvidia NF4 SLI X16, AMD K8 and newer architectures can support the memory swap function.

2. Installation of Windows XP Pro X64 Ed. (64-bit), Windows Vista 64, or other OS which can provide more than 4GB worth of address space.



Note: According to the latest Change Log published by Microsoft, Windows Vista 32bit SP1 will display the installed amount of RAM. This is a display change only.
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