Question

Hi,

I've the following machine configuration:

Intel Core 2 Duo E6300

1 * 2048 MBytes memory chip

2 * 1024 MBytes memory chip

1 * Radeon HD 4870

Motherboard : Gigabyte 945P-S3

I've Windows7 RTM 64 bit installed.

In both Windows & Bios I've 3.25GB available.

How can I enable it support 4GB ?

EDIT: I've sort of upgraded the CMOS version, and Windows acknowledges I've 4GB but is using only 3.25GB.

I guess it is Hardware after all ?

Thanks

Ariel

Answer 1

I'm fighting the same battle right now. Pretty sure we're hosed with the i945 chipset. Granted, I'd love to be proven wrong!

Answer 2

Your BIOS needs to support memory hole remapping.

Memory hole is there since all devices must fit in 32-bit address space during boot (since BIOS is not aware whether you will use 32-bit or 64-bit OS later). Remapping takes care to move affected memory to memory area after 32-bit boundary.

I would check whether new BIOS firmware is available if that setting is not in your current BIOS firmware.

Answer 3

Windows 7 x64 should recognize that RAM with no fiddling required.

If the BIOS doesn't recognize all 4 GB, there's no chance Windows will see it. It's possible that the reason they provide a memory support list is because the board is very choosy.

I would each of your ram sticks individually, to make sure the BIOS sees them correctly.

Now that I'm thinking about it, the SU guys are going to have a lot more experience with this.

Answer 4

Josip is correct that the BIOS with memory hole remapping is necessary. As Chris_K tries to say your hardware must also to be able to physically address more than 4GB see KB929605. I believe that the Intel 945 chipset family cannot do this. So, sorry to say your out of luck.

Answer 5

It looks like the 945 chip set doesn't support more than 4 GB of address space (and some versions only 2GB). So you end up with the same limitation as Vista 32 bit - you won't be able to use all of 4 GB of your RAM since address space is used for more than just RAM.

From the Intel 945 chip set datasheet page 24:

The (G)MCH supports 32-bit host addressing, decoding up to 4 GB (2 GB for the 82945PL/82945GC/82945GZ) of the processor’s usable memory address space

And of page 205:

Addressing of memory ranges larger than 4 GB (2 GB for 82945GC/82945GZ/82945PL) is not supported

Answer 6

/PAE switch in the Boot.ini may help you

Answer 7

The manual for your motherboard doesn't say it is a requirement, but it does advise using the same size memory modules. It's possible that having 1gb modules being scanned first is preventing it from detecting the larger 2gb module.

I would try swapping which bank the modules are in ( 1x2gb <-> 2x1gb ) and see if that helps, failing that I think you just need to get two 1gb modules to replace your existing 2gb module.

Of course, the up-side of the latter would be that you'd re-enable dual-channel and get faster memory use of the system.