4.00GB (3.25GB usable) in Windows 7 x64

I have set up Windows 7 Ultimate 64-bit on my PC. I have 4GB RAM and my BIOS states the correct amount (4096MB), but Windows (System Manager) says I have 4.00GB (3.25GB usable).

This seems to be a popular issue, and I have looked for an integrated video card (integrated with my chipset) to disable but haven't found anything.

What else can be preventing me from seeing all 4GB? When I had Vista 32-bit, it would say 3.25GB RAM not 4.00GB (3.25GB usable). I have a 64-bit CPU and when I bought my RAM, I used a compatibility tool from Crucial (the memory vendor) to test how much memory my PC can support and 4GB was the answer (this was a Windows app I think).

Chipset is Intel(R) G33/G31/P35/P31 Express Chipset PCI Express

In the BIOS, I looked for an onboard video card (integrated) and there was no such thing, but a couple of other onboard devices. There are also no "Resource Mappings" settings.

FURTHER DETAILS:

Chipset
North Bridge: Intel Bearlake G33
South Bridge: Intel 82801IR ICH9R

Maximum Memory Amount   8 GB

Graphics Controller Type    Intel GMA 3100 (Enabled)

I guess the first thing is, how do I disable the graphics controller?

EDIT: This thread indicates the issue is with memory mapped devices, but someone on this thread says that does not apply to 64-bit. The rest of the comments points to a motherboard issue for the guy who started that thread.

Solution 1:

Go into the BIOS, under CHIPSET then go to MEMORY HOLE MAPPING and enable it them save setting to CMOS and reboot. Also go to MSCONfIG BOOT TAB and mke sure MAXIMUM MEMORY is UNCHECKED. That should fix this issue. It fixed it on my Gateway desktop. Hope this helps. (Added by Motodude)

I would see if your BIOS has an "Integrated Peripherals" section. My understanding is that memory mapped devices in x64 operating systems can occupy address ranges outside of your System RAM.

Integrated graphics can and usually does eat into system RAM, though...as it represents actual memory needs. 768MB is a lot, though.

I use Win7 x64 and I have 8GB addressable out of 8GB. Does the system manager say "64 bit operating system" anywhere under how much RAM it shows installed? (My computer, properties). If it doesn't, you could be using the x86 version and not the x86-64 version.

Solution 2:

Run MSCONFIG, open the Boot tab, click Advanced Options, make sure that Maximum Memory is not capped.

Solution 3:

Look in your BIOS and see if there a setting for something like "Memory Remap" or "Memory Hole"? If so it should be enabled.

What is going on (if this is the case) is that PCI devices need address space below 4GB. The setting will some of your RAM to address space above 4GB so it is still accessible.