First let me just start off by saying that I have read a couple of other threads on these boards and seen a couple of answers to my question but they either weren't addressing my particular system or weren't making sense to me or flat out didn't work.

As stated, I am currently using an HP Pavillion dv9260nr.

I have had the system for about 9 mos but I just upgraded my HD to a Seagate Momentus 7200.2 ST9200420AS 200GB 7200 RPM 16MB Cache SATA 3.0Gb/s Notebook Hard Drive - OEM purchased from newegg.com here: http://www.newegg.com/Product/Prod [...] 2-148-307.

I am also in the process of upgrading my RAM to 2 modules (4gbs) of Kingston 2GB 200-Pin DDR2 SO-DIMM DDR2 667 (PC2 5400) Laptop Memory For HP/Compaq - Retail also from newegg.com here: http://www.newegg.com/Product/Prod [...] 0-134-623.

I installed the HD first and got a fresh install of Vista 64-bit just fine. I got all the updates installed (including 929777 which is supposed to address the 4gb issue). I installed the memory and went to a blue screen at boot up. After doing some more research I found that my bios was out of date so I flashed it with the latest version from HP's site.

Upon rebooting my bios reads 4gb but my system reads 3. I have heard here and elsewhere that HP is diverting the missing gb for video memory but this explanation just doesn't make sense to me. I have had my system set up with 2 gbs (out of the box), 3gbs (while trouble shooting my RAM modules and blue screen error) and now 4gbs. If the above explanation is accurate then why didn't my system read 1gb when 2gbs were installed or 2gbs when 3 gbs were installed.

If anyone could please either help me get my system to read the full 4gbs or offer up a more detailed explanation for the missing gb it would be greatly appreciated!

In 32 bit Windows operating systems, the total addressable space available is 4GB. If you install a total of 4GB worth of RAM, the system will detect/use/display less than 4GB of total memory because of address space allocation for other critical functions, such as:

- System BIOS (including motherboard, add-on cards, etc..)
- Motherboards resources
- Memory mapped I/O
- Configuration for AGP/PCI-Ex/PCI
- Other memory allocations for PCI devices

Different onboard devices and different add-on cards (devices) will result of different total memory size. e.g. more PCI cards installed will require more memory resources, resulting of less memory free for other uses.

This limitation applies to most chipsets & Windows XP/Vista 32-bit version operating systems. Again, this is a limitation of the Operating System not having enough address space to allocate to the system *and* the RAM. Not allocating address space to devices renders them inoperable. Not allocating addresses to RAM simply results in the unaddressed section not being used in an otherwise fully functional computer. Therefore the OS designers assign RAM last.

We can have long debates about mathematical fundamentals and discussions about why the original Windows designers couldn't allocate the full theoretical max of 36 bits of address space so that users today would be able to use more resource. But at the end of the day, the designers and engineers 'Didn't Then'. So we 'Can't Now'.


If you install a Windows operating system, and if more than 3GB memory is required for your system, then the below conditions must be met:

1. A memory controller which supports memory swap functionality is used. The latest chipsets like Intel 975X, 955X, Nvidia NF4 SLI Intel Edition, Nvidia NF4 SLI X16, AMD K8 and newer architectures can support the memory swap function.

2. Installation of Windows XP Pro X64 Ed. (64-bit), Windows Vista 64, or other OS which can provide more than 4GB worth of address space.



Note: According to the latest Change Log published by Microsoft, Windows Vista 32bit SP1 will display the installed amount of RAM. This is a display change only.

I understand the limitations of a 32 bit OS but I have the 64 bit Vista Ultimate OS in my system and I am still having the problem. I also understand that memory can be allocated for other things but why is it that when I had 2gb of RAM installed my bios and my system both showed 2gb installed (ame with 3gb) but now with 4gb my bios says 4gb but my system says 3gb?

Is your MotherBoard capable of addressing more than 4G of memory, and if so have you enabled memory remapping (or memory hole, or whatever it maybe called) in the BIOS? If the MB is only able to address a max of 4G of memory you are out of luck.

That's kind of what I was afraid of. I have seen the memory remapping workaround posted elsewhere but I have no such options available to me in my bios and HP maintains that 2gbs is the max RAM supported even though my system is showing 3 avail atm and other people have said they upgraded their HP laptogs to 4gbs (although although everyone I have found who said they made the upgrade also said they only show 3gbs avail). Oh well...thx for the responses anyways.

What it comes down to is some of the devices communicate with the processors using memory addresses (called IO mapping) and as you know this reduces the total amount of system memory that is accessable to the processor. Even though 64 bit OSs can address more memory if the hardware does not physically implement the additional addressing you are back in the same situation. Take comfort in knowing that systems that support 8 GB of memory (max) cannot use 8 GB of memory for the same reason - IO mapping eats into the system memory. When enought people start to populate their 8 GB MotherBoards with 8 GB of memory we will see complaints about not having all of the 8 GB available.

I have this same laptop...

4gb only costs about 70 dollars today from newegg.

If the laptop only reports 3gb avalible for use, then is it even worth it to buy it?

2gb for me is fairly slow and it lags often; will i notice any difference with 1 extra gb?

In order to solve this issue, just install Vista SP1. I have an HP and Acer, both with 4GB of ram and they both report 4GB in the bios and systems under control panel.
I am new to this forum.
Thanks,

Vista SP1 only changes the amount of installed memory that can be reported by Windows. It does not change the amount of memory that is available for use. In the OP's case, his HP dv9260nr uses the Intel 945 chipset, which is hard limited to a maximum of 32-bit physical address space (4GB). Installing SP1 will make Windows report all 4GB, but it will not utilize any more than it was prior to SP1. This is a chipset limitation in the Intel 945 that no software can solve, not even 64-bit OS.

I was looking for an answer for the same issue ... I have an HP Pavillion dv9260us which is basically the same laptop that's under discussion, Win ultimate 64-bit, comes with 2gb of ram ...

Just upgraded to 4gb of ram, same deal, 4gb in bios, 3gb shown in windows.

tcsenter, are you saying that, since the cpu can't do 64-bit addressing, they sold us a 64-bit OS that can't be used as a 64-bit OS due to cpu limitations? If that's the case then I'm not happy with HP!

Or, is it possible that this extra gig of ram is relocated to my videocard? When I had 2gb installed dxdiag said my (approx)total memory was 512mb (iirc), now with 4 gb (and only 3 showing in win) it says 1528mb. It's a gf Go7600 btw, 256mb.

Integrated graphics on your lappy, I'd bet.

but dedicated memory tho, shouldn't be shared..

I don't know how much more clear and specific I could have been when I wrote:

"HP dv9260nr uses the Intel 945 chipset, which is hard limited to a maximum of 32-bit physical address space (4GB). Installing SP1 will make Windows report all 4GB, but it will not utilize any more than it was prior to SP1. This is a chipset limitation in the Intel 945 that no software can solve..."

Which part are you 'fuzzy' about?

I'm not fuzzy about anything. The only thing i was questioning was HP selling us a laptop with a 64-bit OS which can't work at its full potential, in my eyes making it a bit pointless. They should've sold us a cheaper version, eg 32-bit, which can work at its full potential.

No need to get on your high horse.

If the only thing you were questioning was HP, why was the question directed specifically at me?

There is no price difference between 32-bit and 64-bit Vista SKUs. And the problem has nothing to do with the CPU. Vista 64-bit would not run if the CPU did not support it.

I just happened on to this forum. Are you guys saying that I can upgrade my dv9260nr with vista 64 to 4gb ram? I was told the max was 2gb.