[Grim Keeper]

Okay ive studied computing to 1st year University level and as far as i know the amount of RAM your computer can address is 2^(size of address bus), so if you are running a 32 bit O/S then its 2^32.

3^32 = 4gig

but its only possible to support 3gig on a 32bit O/S why is this?

[Advertisements]

In a nutshell the operating system cannot use the extra 0.8Gb of memory because it's all tied up in the PC's architecture.
Which basically means the missing memory is reserved so the computer can talk to the rest of the hardware.
It is not a Windows issue as such - it's a a limitation of the hardware. It just ends up being a Windows issue because 32-bit hardware solutions have been around for over ten years now and its only now its beginning to show its age. 64-bit platforms solve the problem but as we live in a 32-bit environment, the migration to 64-bit will take some time.

Back in the days of DOS, when it were all fields round 'ere, even DOS has a reserved memory chunk for the hardware. Every PC had 640k of base memory, and everything over that was extended memory, of which 384k was reserved for the hardware.

Edited by Neil Jones, 15 December 2008 - 04:39 PM.

[Neil Jones]

In a nutshell the operating system cannot use the extra 0.8Gb of memory because it's all tied up in the PC's architecture.
Which basically means the missing memory is reserved so the computer can talk to the rest of the hardware.
It is not a Windows issue as such - it's a a limitation of the hardware. It just ends up being a Windows issue because 32-bit hardware solutions have been around for over ten years now and its only now its beginning to show its age. 64-bit platforms solve the problem but as we live in a 32-bit environment, the migration to 64-bit will take some time.

Back in the days of DOS, when it were all fields round 'ere, even DOS has a reserved memory chunk for the hardware. Every PC had 640k of base memory, and everything over that was extended memory, of which 384k was reserved for the hardware.

Edited by Neil Jones, 15 December 2008 - 04:39 PM.

[Grim Keeper]

its not actually 0.8gig of memory it uses, but memory addresses right?

Edited by Grim Keeper, 18 December 2008 - 08:08 AM.

[TIP83]

I thought that the memory you are "losing" is close to or equal to the memory on your Video Card.
I don't know the details of it but it sounds right to me.
I'm using Windows XP SP3 32-bit and my video card is the nVidia GeForce 280 GTX 1GB.
Under the general tab of System Properties it reports 3.00GB of memory. While I have 4GB OCZ DDR3 installed.

Since a 64-Bit O/S removes this limiter I'll be upgrading to Vista Ultimate SP1 in the next week.
This will make the rest of my computer feel at home also:
Please let me know if any of you have had problems with this Hardware being compatible with Vista 64-bit

nVidia 790i Ultra SLI
4GB DDR3 2000MHz
nVidia Geforce 280 GTX 1GB
Intel Q9550 OCed to 3.08GHz (need H2O cooling to push to 4GHz)

Hope this helps.

[lurky]

32 bit OS's support four gigabytes. As Neil stated, some of that is tied up in the architecture. Basically, the video bus and a couple other minor devices are going to steal a little bit of that to accommodate for their needs. Which is why it shows a difference relative to amount of video memory your pc has.