Vista Problems - RAM

[Voodoo_Magic]

I have 4 sticks of Corshair XMS2 1024mb installed.

In windows XP it only said i had 3.25GB but i new the cap for XP was around 3.5gb so i wasnt to bothered. But know in Windows vista is only counts my ram as 3326mb, i know there not always exact to the penny, but to be a gig out is a tad to far ^^.

So, any help is making vista count my ram correctly?

Image attached

[Mighty Max]

32 bit system?

ia32 can only address 2^32 bit, which is 4GiB.
PCIe, PCI, AGP and alike have "memory mapped io" reducing the maximum addressable RAM by the amount of addressable IO.
Including big things like GFX RAM.

Only with the use of 64 bit extension (AMD 64) and the 64bit extended windows version can address more (36 bit) of RAM, which would be 64GB.

True 64 bit systems alkow more 'course.

:edit: just looked it up, even the EM64T - unlike the AMDs 64 versions - are not able to address more then the 32 bit on the IOMMU, so still limited to 4GiB

[CMaster]

Right lines Mighty Max, but not entirley accurate. You can address 2^64 different memory blocks with a 64 bit OS. Although there is likley some hardware restrictions below that, relatetd to the width of the address bus and the x86 processor design restricts block size to 8 bits (one byte) dissapointiingly.

Voodoo - basically, windows is assigning the addresses first to things that need it (so video card memory, other expansion cards, I/O devices etc) and then whatever is left over (out of a maximum 2^32 addresses) is given to your RAM. So you can either start pulling out expansion cards, or get a 64 bit OS (assuming your processor supports it). Maybe one day we'll get a paradigm shift where someone makes the PC into a say 32 bit computer or something - because its starting to seem a bit silly putting 64 bit processors into 8 bit computers.

[Voodoo_Magic]

Bah, ill re-install xp x64 then

Thanx, i new it was around 4gb for x86 but didnt realise other devices was classed within that limit, makes sense tho

Any1 know what the max Ram XP / Vista can support? (x64)

[CMaster]

Any1 know what the max Ram XP / Vista can support? (x64)

In theory, it allocates a 64 bit unsigned int for addressing, so 2^64 addresses, which in a PC means 2^64 bytes. I'd think its reasonable to guess that your hardware can't do that though.

[Mighty Max]

Right lines Mighty Max, but not entirley accurate. You can address 2^64 different memory blocks with a 64 bit OS. Although there is likley some hardware restrictions below that, relatetd to the width of the address bus and the x86 processor design restricts block size to 8 bits (one byte) dissapointiingly. but

That is why I spoke of ia32 as the base, this is the hardware restriction. The 100% compatible hardware has 32 addresslines leaving the MMU.

Even the non 64 bit extended hardware i.e. Pentium 1 could internally address about 8GiB of RAM. ( 32 bit base address in a segment descriptor added by another 32 bit of offset -> 33 bit addresses) but due to the missing line, memory gets wrapped around (just like at the A20 of the early days)

On the other side, PAE as a standard allows exchange blocks, like consoles do it since the GB classic, allowing a maximum of 16* 4GiB Blocks but that's basically a "dirty hack" to extend the limits

[Mighty Max]

Bah, ill re-install xp x64 then

Thanx, i new it was around 4gb for x86 but didnt realise other devices was classed within that limit, makes sense tho

Any1 know what the max Ram XP / Vista can support? (x64)

If http://compreviews.about.com/od/memory/a/Vista4GB.htm can be trusted:


The 64-Bit version of Windows Vista does not have this same 4GB memory limit. Instead, each 64-bit version has a limit to the amount of addressable memory. The different 64-bit versions and their maximum memory are as follows:

* Vista Basic: 8 GB
* Vista Home Premium: 16 GB
* Vista Business/Enterprise/Ultimate: 128+ GB

[Voodoo_Magic]

If http://compreviews.about.com/od/memory/a/Vista4GB.htm can be trusted:

thx, i have business x86 & x64 ..

But if history is anything to go by,im sure basic can be "patched" to run more