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The Corsair Support Forums > General Corsair Topics > General Questions
Total memory question??

DOMANDA

Hi all,

I've looked all over and don't understand, hope you guys can clarify for me.

I'm planning on adding Memory to my system but now I'm not sure how much. I'd like to minimize the page file so I can keep everything in virtual memory.

In Windows Vista and XP 32-bit OS what is the approximate amount of ram available. I see a lot of talk about 2Gb versus 4Gb and approximate available physical ram left for applications depending on the system build to be about 3Gb for a system with 4Gb.

So to make it easier for me to understand can someone finish the equals for me? I'm not sure if adding another twin 8500 C5DF is a good idea or not. I'm planning to move to Windows Vista Home Premium in the near future, I have XP Pro right now.

2Gb = ? of physical ram available.
3Gb = ? of physical ram available.
4Gb = ? of physical ram available.

Thanks ahead of time.

RISPOSTA

Let me clarify.

Your computer has many methods in which to use memory. There are memory storage and caches all over the motherboard. These devices contain some of the below method of storage:

* RAM
* ROM
* Cache
* Dynamic RAM
* Static RAM
* Flash memory
* Virtual memory
* Video memory
* BIOS


For example, your sound, video, keyboard, chipset caches, I/O controller (IDE, SATA, etc) caches . . . Now these device with discrete and cache RAM need to have their "Addresses" so that the computer knows where they are in order to query and access them.

You computer also has System Resource Memory. Consider this as an index of addresses that tell the computer where everything is for access as mentioned above. The computer needs to know that a certain boundary of addresses will contain certain functions to perform when commanded.

Memory-mapped devices (such as your video card) will use some of that physical address space, as will the BIOS ROMs. After all the non-memory devices have had their say, there will be less than 4GB of address space available for RAM below the 4GB physical address boundary. Now a 32bit Operating system such as Windows XP 32bit and VISTA 32bit have the ability to access 2^32 bits = 4GB. Now if you have an 8800GTX with 768MB of DRAM, then that memory must be addressed in the space of the 4GB and you lose some of the system dram to the addressing. This continues with all other devices, leaving you with less than the 4GB. Since Windows can address up to 4GB, then with 3GB, there will be the 3 --> 4GB mapping so you should not lose that DRAM with 3GB unless your devices demand it. For example, SLi with 2 X 8800GTX 768MB will certainly take away from the 3GB.

Hope this helps to clarify things a bit.