Does 64 bit Win get more mem under 4 gig than 32 bit?

vbimport

#1

I have seen how you have XP 32 bit with Nvidia and with 4 gig of RAM you only see 3.50 gig.

If you run Windows 64 bit is it still only 3.50 gig? Or does 64 bit OS make it even 4 gig instead?

Thank you


#2

The answer is ‘Maybe’. If the video card is using 500 MB of shared RAM then no. A 64 bit OS can address more RAM than a 32 bit so if the video memory is separate then the answer is yes.


#3

I have found that if Windows 7 64 bit is installed the system properties show a full 4 gig of available memory. 32 bit only 2.75.

Thank you for helping


#4

32b OS’s can only address 4GB of address space, unless they have PAE.
You lose a good chunk of the 4GB RAM address space to I/O for devices & etc, so in effect, you usually get about 3.2-3.5GB of ram only.

64b OS’s can address 2^32 times the address space of a 32b OS, which is a crapload (for now) so you’ll get your full ram available … eventually 64b will run out of address spaces, as IO increases & etc.

It won’t be for a few years though - it’s been 20 odd years since 16bit processors and 640KB was more than enough for everyone :wink:


#5

Yes a 64bit OS can use and see up to 128GB of ram. :iagree:


#6

Physical Address Extension present in all 32 bit XP installs I have testing. 512 meg Nvidia 8xxx card has 3.5 gig of 4 gig available. GTX 295 leaves 2.75 gig of 4 gig available.

I am unready for a full move to 64 bit so 32 bit limitations will have to do for now.