Just how much RAM does 32-bit Windows support?

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Vercogen

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I bought Windows 7 32- bit recently, and one of my friends mentioned that the 32-bit version only support up to 3GB of ram where I have 4GB.

I the got hold of this article that stated differently?

Any comments?
 
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In short, yes... sort of. Apparently windows needs to use some of the addressing space to be able to address GPU RAM as well. So if you have 4gb RAM, and a 512mb GPU, you won't see all of your RAM.

The PCI memory addresses starting down from 4 GB are used for things like the BIOS, IO cards, networking, PCI hubs, bus bridges, PCI-Express, and video/graphics cards. The BIOS takes up about 512 KB starting from the very top address. Then each of the other items mentioned are allocated address ranges below the BIOS range. The largest block of addresses is allocated for today’s high performance graphics cards which need addresses for at least the amount of memory on the graphics card. The net result is that a high performance x86-based computer may allocate 512 MB to more than 1 GB for the PCI memory address range before any RAM (physical user memory) addresses are allocated.
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Archer said:
In short, yes... sort of. Apparently windows needs to use some of the addressing space to be able to address GPU RAM as well. So if you have 4gb RAM, and a 512mb GPU, you won't see all of your RAM.
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This. 4GB - GFX Ram.

Apparently it is *technically* possible to access more on a x86 box with this: http://en.wikipedia.org/wiki/Physical_Address_Extension but I don't think thats every used for desktop PCs.
 
32bit OS can only address 4GB of memory, including all memory on display adapters, sound cards, RAM, etc. If you have a 1GB VGA card, then it has to map that memory into the 4GB limit, thus reducing the amount of RAM your system can see.
 
In my experience it depends on the motherboard and the RAM used. These are all theoretical limits... but I have had one motherboard with 4 Gb of RAM can only see 3 Gb. And I have had another motherboard with 4 Gb of the same type of RAM could see 3.5 Gb. I think you will find it varies with manufacturers, Bios support and RAM type.
 
Funny... to think we started off with 1Mb RAM... back then we had the 640k memory limit.

Some things never do change. :D
 
A 32bit Operating system can only support up to 3.4GB of ram. You should upgrade to a 64bit OS anyway since one day everyone will be moving up to a 128bit os.
 
Garyvdh said:
I think you will find it varies with manufacturers, Bios support and RAM type.
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Exactly ! And it also depends on the extent to which the BIOS supports W7.

I tried W7 64-bit on my Sony VGN-SZ38 with 4GB RAM - it would still only support 3.2GB RAM - presumably because of the BIOS.

And Sony don't have a habit of providing proper support for older equipment - they want you to buy a new computer !!!

So, also very little 64-bit driver support by Sony, so I just put W7 32-bit on the computer - that is OK, but still had problems with the drivers (mostly used Vista drivers).
 
Garyvdh said:
In my experience it depends on the motherboard and the RAM used. These are all theoretical limits... but I have had one motherboard with 4 Gb of RAM can only see 3 Gb. And I have had another motherboard with 4 Gb of the same type of RAM could see 3.5 Gb. I think you will find it varies with manufacturers, Bios support and RAM type.
Click to expand...

How do check to see how many ram your motherboard "see"
 
Vercogen said:
How do check to see how many ram your motherboard "see"
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1) First check the manual to see what the board supports, type and maximum amount.

2) The go to Manufacturer's website and see if there is BIOS upgrade.

3) Then install more than 4 Gb.. preferably using ALL the slots if you can... and boot into Windows 32 Bit. Then check the system properties tab.

BTW... I have also had some motherboards where the BIOS reported a different amount to what Windows could see (both ways).
 
Vercogen said:
How do check to see how many ram your motherboard "see"
Click to expand...

The documentation will tell you how much RAM the board can address. Just remember that as mentioned above, your motherboard has the same limitations when it comes to addressing memory, in that the total supported memory includes ALL memory that your machine needs to address. If it maps you VGA memory into the 4GB limit, then it cannot map that same space into RAM....

As a rule of thumb, if you want 4GB of RAM, then find a board that supports 8GB. If you want 8GB, then find a board that supports 16 etc....
 
I have that silly 4gb limitation on my old mobo, running 64 bit windows.
3GB in use and 3.5gb available and am using 4gb ram with 512mb gpu memory.
I still have an advantage as 3gb gave me no duel channel until i shoved in the 4th gb[i presume].
Wouldn't the 4th gig, even on 32 bit windows still give a performance boost with pae enabled with a 3.5 gig visible rig?
 
demon angel said:
I have that silly 4gb limitation on my old mobo, running 64 bit windows.
3GB in use and 3.5gb available and am using 4gb ram with 512mb gpu memory.
I still have an advantage as 3gb gave me no duel channel until i shoved in the 4th gb[i presume].
Wouldn't the 4th gig, even on 32 bit windows still give a performance boost with pae enabled with a 3.5 gig visible rig?
Click to expand...

No. PAE allows a machine to use the 4 extra bits on a processor to make the more memory available (Physical Address space) - however the OS can still only address 4GB (virtual address space of 32bit OS). This 4GB is split into 2GB of RAM for a single thread and two gigs reserved for kernel memory (this cannot be reassigned unless you use the 3g switch).
 
^^ Not correct e.g. Windows 7 can address up to 192GB of RAM.

Total addressable memory for 32 and 64 bit:
2^32 / 1024 / 1024 = 4096MB
2^64 / 1024 / 1024 = 17 592 186 044 416MB
 
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