can I utilize all memory?

we have a new 64bit tower PC which came with 8GB memory, but we had to install a 32bit version of Windows Seven. Does that limit the amount of memory available to beneath the 4GB ceiling please?

so, to be clear, we need to put a 64bit OS on there to access all the available memory.. yes?

Oh, I see from unreal's post that yes, this is so. Thanks guys (sigh)

Yes.

pawz7 said:

so, to be clear, we need to put a 64bit OS on there to access all the available memory.. yes?

No.You can use PAE for 32 bit system.
But I would suggest you to install 64 bit system.

don't want to go down the PAE road - from what I have read in the past it is not recommended and could lead to instability. We will probably go fo a 64 bit OS, as you say, eventually. He isn't a gamer or power user, so it isn't urgent, and being an i5, the new box is still much more responsive than his previous 32bit machine. Ho hum, thanks for the help folks.

In any computer system there are to limitations on how much RAM it can access:
1. How much RAM the hardware can provide to the OS.
2. How much RAM the OS can access.
The usable limit is whichever one is smaller. Neither the OS nor the hardware can override the limitations of the other.

The use of PAE will not allow a 32 bit client version of Windows to access more than 4 GB RAM. In reality it is somewhat less than that. Doing so would require the use of a modified kernel which would be a violation of Microsoft's EULA and I will not discuss it. PAE permits a 32 bit CPU to access more than 4 GB RAM but that does you no good unless the OS is an active participant in this. 32 bit client versions of Windows by design will ignore all memory above 4GB and the use of PAE doesn't change that. Using PAE will allow some devices such as a RAM disk to access RAM above 4 GB but applications cannot.

LMiller7 said:

The use of PAE will not allow a 32 bit client version of Windows to access more than 4 GB RAM. In reality it is somewhat less than that. Doing so would require the use of a modified kernel which would be a violation of Microsoft's EULA and I will not discuss it. PAE permits a 32 bit CPU to access more than 4 GB RAM but that does you no good unless the OS is an active participant in this. 32 bit client versions of Windows by design will ignore all memory above 4GB and the use of PAE doesn't change that. Using PAE will allow some devices such as a RAM disk to access RAM above 4 GB but applications cannot.

That's not correct, entirely. PAE was created specifically to allow 32 bits OSs to use more than 4 GB of RAM (up to 64GB). It's true that usage of PAE requires a modified kernel, but ALL versions of Windows conveniently include such kernel (it's the file NTKRNLPA.EXE, opposed to the normal kernel NTOSKRNL.EXE both found in system32). The only thing that requires patching is the bootloader that chooses between these two kernels (and that's what may come with a license problem). Once that's done, everything can use the full memory installed on the system.

But in itself, 32 bits Windows is fully capable of using up to 64 GB of memory but MS ridiculosly limits such ability to server editions (look at the memory capabilities of Windows 2008).
For a more detailed reference on the topic, look here:
Licensed Memory in 32-Bit Windows Vista

Now, back to the central topic, while it's possible to make Windows x86 recognise and use the full memory, I would opt to go for a x64 version. That's because the 64 bits version includes support for some extra security features (DEP and driver signing enforcement for example) and allow for 64 bits native processes, which can have somewhat improved performance for some programs, among other things.