Windows 7: Hardware reserved Memory?

I had 2 gb of ddr3 ram installed before, yesterday i added 2 more gb but the system uses only 3.24 gb and the rest is reserved for hardware. I hope it is used for graphics memory but i have an external graphic card of 1 gb video memory. How to release this memory. I have searched many forums and they suggested to uncheck the maxmemory in msconfig, that didnt work.

Also they asked to enable memory remapping in bios, but my bios doesnt have that option. My OS is windows 7 ultimate 32 bit.



I'm attaching the screenshots below.

There are a lot of things that can cause this. However since you are on 32 bit windows 3.2 gigs is the maximum it will make use of. This is a limitation in the 32bit system not an actual error per say.

thanks for the reply, so no way for using the remaining 750mb ram . I have another question.. hope you saw the screen shots i attached it shows that i have 6+ gb of virtual memory. Is it really necessary to have such huge space since i've already have 3.2 GB of ram..

It's because you're using 32bit OS. I have the same as you when was using 32 bit, but now I don't.

Have a look at this and note the "Hardware Reserved" section.... Investigate memory usage with Windows 7 Resource Monitor | TechRepublic

You might also want to see these posts....

- 4 GB of Physical Memory but 1.74 GB Usable

- 4 GB of Physical Memory but 1.74 GB Usable

The memory is not hardware reserved. 32-bit Windows 7 deliberately prevents you from using it even if PAE is enabled.

To demonstrate this as fact...

1) Download and install Gavotte Ramdisk 1.0.4096.5
2) Create a PAE ramdisk
3) Use ramdisk
4) Point proven

On my 4GB 32bit system Gavotte Ramdisk is able to use 990MB of supposedly 'hardware reserved' RAM. This is a fact - not something that I read somewhere.

If you're willing to forego the use of hibernate or hybrid-sleep (sleep works fine and I have a UPS so I don't care) then you can create an additional page file on the ram disk which Windows will prefer due to the fact that it will likely be at least 20 times faster than your HDD.

How to use full 4GB RAM in Windows 7 32 Bit (Gavotte RAMDisk in Windows 7) | Homepage of Jens Scheffler

The fact that you can only use 3.2GBs is not a RAM problem per se but an address space problem. A 32bit system has only 4GB-1 of address space and everything has to fit into there. And that also includes a graphics card with its own RAM. It has to be addressed somehow.

Here is a bit more about all the other stuff that needs address space: Maximum Memory in 32-bit Windows Vista : Windows Vista and Windows 7 Help

You're right on one point: none of the memory is actually reserved for anything. What is reserved is a portion of the 32-bit address space just below the 4GB barrier. (You can't address more than 4GB with just 32 bits, it's numerically impossible.)

Where it gets tricky is that modern motherboards actually have at least a 36-bit address bus (from what I understand) - the 4 additional bits would allow access to 16 blocks of 4GB each for a total address space of 64GB. This is where PAE (physical address extension) comes in, using exactly these extra bits to allow a 32-bit Windows system to access memory that was mapped above 4GB (which is possible and even normal even if only 4GB of physical RAM is actually installed).

Using PAE, however, Windows could access memory that was remapped by the BIOS to reside in an address space above 4GB. The reason it won't is because far too many 32-bit device drivers were developed under the assumption that there'll never be any memory addresses beyond 4GB of RAM available, and if these drivers suddenly had to deal with memory addresses above 4GB they'd crash and burn, bringing the system down with it.

So Microsoft had to implement this classic 3.xx GB limitation in all 32-bit versions of Windows, so that no address space above the 4GB barrier is visible to anything running on the system.

That is, unless something explicitly requests access to the "invisible" memory, which is what Gavotte Ramdisk does.

So, the reason Windows only uses 3.25GB out of 4GB is because only 3.25GB are mapped within the address space below 4GB. The rest is mapped above 4GB up to 4.75GB, while the address space between 3.25GB and 4GB is mapped to all PCI devices and motherboard resources so they can exchange data with the system through that address space. This is the only way to ensure 32-bit drivers will work correctly, by not exposing them to the >4GB address space. Thus the artificial limitation.

But using PAE, Windows is able to allow Gavotte Ramdisk to access the >4GB memory and use it for the RAM disk.

So, it is therefore... hardware preserved. The fact that you can use a 3rd party program to get around it doesn't negate the fact that "Windows 7 deliberately prevents you from using it even if PAE is enabled"

I'm just reporting what's stated here - Investigate memory usage with Windows 7 Resource Monitor | TechRepublic

And here - Windows 7 memory usage: What's the best way to measure? | ZDNet

Anyway I'm not going to call myself a memory expert so....

And yes WHS, it is a address space thing.

Edit: Snipped, misread last sentence as a question

The RAM between 3.25GB and 4GB is absolutely not hardware reserved; it's remapped (as Corazon stated) to above 4GB so that the devices in the machine can be accessed through memory-mapped I/O in the region below 4GB. The remapping is necessary because the PCI-Express bus still only has 32bit address lines and can't address memory above 4GB. This is true even in 64bit Windows, Linux or whatever - it's not done by the operating system.

By contrast, every processor since the Pentium-I-can't-remember-which-one-exactly has been capable of 36bit PAE addressing (that's 64GB)

The claim that allowing PAE addressing in Windows causes (or caused at some point in the past) problems with some drivers may well be true for drivers that are not written following the Windows DDK specification, with the 'gotcha' being that realistically, there's no way to tell in advance of them crashing your system. For that reason I more-or-less accept Microsoft's stated rationale for hobbling PAE on desktop Windows since XP-SP3, but the fact remains that there exists a way to use this memory in a way that makes badly written drivers irrelevant, so I often feel the need to point this out.

It's interesting to note that Gavotte Ramdisk is based on a sample ramdisk program provided by Microsoft in the Windows DDK a long time ago.