Which "Windows' better handles 4GB of mem?

[yankeeDDL]

I read in some forums that Windows XP can't handle 4GB of memory and uses, instead, only 3.3GB
Here are one link:
http://bink.nu/forums/8805/PrintPost.aspx
but if you do a search "windows XP 4GB ram limit" you will see tons of forums which discuss this issue.
The fact is, I just assembled my nes PC and I got 4GB of memory on Win XP.
Now, check this:
- the BIOS recognizes all 4 GB
- when I check the system properties, it shows 1.93GB of RAM (!?!?!)
- system information says I have 4096MB of total physical memory.
- task manager, under the "performance" tab shows 2030896K of total memory which is 1.936GB

What is going on?

 

[pat]

I read in some forums that Windows XP can't handle 4GB of memory and uses, instead, only 3.3GB
Here are one link:
http://bink.nu/forums/8805/PrintPost.aspx
but if you do a search "windows XP 4GB ram limit" you will see tons of forums which discuss this issue.
The fact is, I just assembled my nes PC and I got 4GB of memory on Win XP.
Now, check this:
- the BIOS recognizes all 4 GB
- when I check the system properties, it shows 1.93GB of RAM (!?!?!)
- system information says I have 4096MB of total physical memory.
- task manager, under the "performance" tab shows 2030896K of total memory which is 1.936GB

What is going on?

32 bits os and cpu can only use 2^32 bits (4 gigs) total adress space. since everything, from video card to usb devices use some adress spaces, then there is no more 4 gigs available for ram.

64 bits os and cpu will be able to use way more than 4 gigs of ram...(2^64)

 

[yankeeDDL]

I'm not really convinced about that: all other systems I saw show the actuall total physical memory in the "Syestem Properties" tab, regardless of they use.
So why would it show only 1.93GB when there are 4GB avail?

Or are you saying that some of the 2^32 addresses are not available because reserved by some hardware?
Even so, 1.93 is << 4: can it be that 2.07GB are reserved? that's less than 2^31 ...

 

[pat]

I'm not really convinced about that: all other systems I saw show the actuall total physical memory in the "Syestem Properties" tab, regardless of they use.
So why would it show only 1.93GB when there are 4GB avail?

I dont know..maybe there is something wrong with th OS memory management or you are using some sort of virtual devices that chop some memroy.

Or are you saying that some of the 2^32 addresses are not available because reserved by some hardware?
Even so, 1.93 is << 4: can it be that 2.07GB are reserved? that's less than 2^31 ...

thats it. 4gigs is the max allowed with 32 bits. running 2 512megs videocard in SLI use 1 gigs of adress space that cannot be use by ram, ie.