A question for anybody. I know enough about computers just enough to be dangerous. Here is the question I my nephew has WinXP and just put in 6GB of ram and it registers 3.5GB if I remember correctly that XP only supports 4GB If he upgrades to Vista will this solve the problem, and if so can he just purchase the "upgrade" vista disc??? Since he likes to re-format his computer every year would this work. I know back in the day you could just stick in your previous version to verify and then put the "upgrade" disc back in to continue to upgrade. Does this still apply??

Depends on the Motherboard.

The motherboard needs to support memory mapping for more than 4gb if I remember correctly.
Otherwise even Vista will just use the 3gb and allocate the rest to video memory and extras.

Oh yeah I guess i should have stated that YES the motherboard can take up to 8GB. It shows correctly in the bios as 6GB.

I read recently that even with Vista it needs to be the 64bit OS version. I don't know how true this is, as it might just apply to the HP computers I was looking at, and they said 2GB was the limit, whereas I always thought it was 4GB.

I guess that doesn't help much though. Sorry.

32bit Vista with SP1 can use up to 4gb but it will alloctae the video memory out of that. So with a 512mb video card your pc will only be able to use 3.5gb.

64bit Vista with sp1 can use up to 8gb.

I guess this would be helpful

http://www.gigabyte.com.tw/Products/Mother...?ProductID=2599

It is my understanding that the maximum amount of memory that a 32-bit OS can address is 4GB (2^32 -or- 4294967295 bytes), and the 3GB to 4GB address space was reserved a long time ago, for memory-mapped I/O, because the "no one would ever have more than 640K of memory" mentality stretched to the 3GB barrier.

For backwards compatibility of processors, so that they can still boot DOS, the 640K to 1MB range, and the 3GB to 4GB are reserved, so even on 64-bit processors, you will lose access to the memory (So, if you have a 64-bit OS and you install 8GB of memory, the OS will only have access to 7GB of it because the 3GB to 4GB range is still reserved).

The 3GB to 4GB range is also a mapping, meaning that if you install a peripheral, like a 512MB video card, that gets assigned an address space of 3.5GB to 4GB, then writing to memory at that location will actually write to the peripheral, and not physical memory. So, if your system has only 2GB of memory, the memory space at 3.5GB will be valid because it will write to the peripheral. However, if you try to write to the memory space at 2.5GB, you will have problems because there is no mapping and you will try to write to non-existent memory.

This still applies if you have installed 4GB of memory; if you write to the 3.5GB memory space, it is mapped to the peripheral, and the actual memory that lies at 3.5GB is inaccessible. As far as I understand it, this is all reserved in the DOS/Windows world, so you may be able to access a full 4GB in *nix OSs???

So, to answer your question, upgrading to a 32-bit VISTA will not gain your nephew access to any more of his memory. Buying the 64-bit version won't work either, unless you actually buy a 64-bit processor as well.

For the most part to above is correct, only ~4GB barrier is caused not by a misconception, but the method of addressing. The only faulty assumptions made by then engineers using 32bit addressing was that we would have migrated to a 64 bit architecture by the time it became an issue. Procrastination and cheap consumer hardware is "at fault" more than anything. The next jump should last us a bit longer as the addressable space is orders of magnitude larger.

For various reasons the above translates into "Windows XP/Vista 32 bit only sees a maximum of 3.5 GB of ram".

Actually I dont believe that that is the case. Windoze VISTA is a classic case in point where an OS is designed to use more consumables in order to boost flagging sales in hardware. You would think after several years of working in 32 bit code that you could get quite adept at making more effective code chains, but that was never the idea. I BETA'ed vista ( as I did with 98 up til now) for MS and the general conscensus was that it didnt matter what resources were used as long as the consumer liked it. 98SE was the most comprehensive BETA they ever went through and it shows. That code was actually an attempt to optimize the code not maker it larger.

Its not the procrastination factor thats killing it. Its the fact that most consumers dont NEED to see 8gb of ram. About 85% of the people out there are happy with what they have for surfing and word processing and the rest are either die hards with big epeens or gamers...or they are using a much more efficient OS.
If it wasnt for my games, I would have abandoned MS a long time ago.

The consumer spoke with XP64..."most of us dont need this". A statement that was echoed by the hardware manufacturers by theirt speed in producing 64 bit drivers. Now that MS has phased out ( forced out) 32 bit, they will now follow up because MS forced our hands.

MS drives the hardware market ...even if we dont want it to.

I agree that sdubb's nephew is limited to 3.5GB of ram in his current setup. Your statement above sounds very final, which does not reflect everyone else's possible configuration. For others who may be in the same boat as sdubb's nephew, I just wanted to add a bit more.

Any 32-bit operating system is limited in it's ability to address a maximum of 4GB of memory. This limitation is an architectural limitation, as the address space of memory is set to be 32-bits. The largest number (address line) that can be represented with 32 bits is 4294967295. Therefore, the maximum memory that any 32-bit architecture can address is 4GB.

Having said that, memory mapping I/O can 'steal' some of that addressable space. Because the system is masking the I/O peripheral as a section of memory, it's mapping must fall somewhere in the 0GB-4GB space. It just so happens that the standard has been to reserve the upper GB in that range. This does not mean that the memory from 3GB to 4GB is lost to the OS. It is only lost if you have any memory mapped I/O peripherals.

So, let's say that you decided to put in an OLD video card into your system; think ISA card. That video card may only have 8MB of memory. If it is memory mapped, it will only take up 8MB of the upper GB of memory. Effectively, the OS will still have access to the full 4GB (minus 8 MB) of memory. If a 256MB card is used, then the OS can access 3.75GB. If a gamer installs a power video card with 1GB of memory, then the Windows OS will map the entire peripheral in the 3GB - 4GB range, leaving the OS with only 3GB of memory to use.

Keep in mind that more than one device could use the reserved space. A 512MB sound card and a 512 MB video card would add up to 1GB of memory mapped devices, leaving only 3GB of memory for the OS.

If you want to see what area of memory a device takes up, just launch the "Device Manager" in windows. Find your peripheral of choice, and select the properties option when you right-click on it. In the properties window, click on the 'Resources' tab to see the Memory Range entries (there may be more than one).

I know, I know, splitting hairs here. I just thought that other people reading this thread might want to know how it all works and what to expect in their situation. They may not have access to 3.5GB if they add more memory to their system.

samuraijack: You are quite correct in that most users should not need this much ram to perform what are broadly considered basic functionality these days. All of this bloat can certainly be argued as only beneficial to software and hardware manufacturers.

Pirin: This is the meat, many giant applications handle their own memory management for precisely the reasons you mention to get around this problem cropping up in earlier systems (remember highmem and derivatives?). Of course having an application duplicate operating system functionality is not he most efficient thing to do, but it gets the job done.

Well you guys have really lost me so here is some more information (he built this computer for gaming)

here is the chip he put in it..... intel core 2 duo processor E4500

will the 6GB of ram work with VISTA 64 bit and use all of it?????

I think that is not possible.....