[gupgup]

Hi,

I'm running Win 7 Pro 32-bit on a Dell Vostro 420. I currently have 3 gb of DDR2 PC2-6400 RAM installed (1x2gb, 1x1gb). I have 2 video cards (ATI HD 4350), one which is PCIe x16 and another which is PCIe x1. Eachhave 512MB of on-board memory.

Resource Monitor shows that of the 3072 MB installed, 1026 MB is "Hardware Reserved" and a total of 2046 MB is available to the system.

My question: If I replace the 1gb module with a 2gb module (for a total of 4gb installed), would the memory available increase from the current value of 2046MB? Would the Hardware reserved allocation remain the same, i.e., 1026 MB?

Thanks for your input!

 

[joeten]

A 32 bit system will support up to 3.25 gb so your at the optimum for ram, I would look at the video cards as a place to upgrade

 

[gupgup]

Thanks for the reply! However, if 32 bit supports upto 3.25 gb, and given that I currently only have 2gb usable (since 1gb of the installed 3gb is hardware reserved), wouldn't adding an additional gig (for a total of 4gb installed) up my usable by the same amount as well? Or am I missing something?

 

[LMiller7]

A 32 bit OS has a maximum physical address space of 4 GB. Most, but not all, of this space can be used to address RAM. A portion of this address space is required for memory mapped hardware and is called "Hardware Reserved". Note that it is the address space that is reserved, not RAM. RAM which shares address space with other things cannot be accessed. If the system has less RAM than the hardware reserved space then almost all of it can be accessed. Only in the event that RAM size exceeds hardware reserved space is there a conflict and some significant portion of RAM cannot be accessed.

The size of the hardware reserved address space is not fixed but depends on the hardware in the system. Typically it will be about .75 GB, leaving 3.25 GB available for RAM but it can be more or less. For simplicity some older systems reserved the entire upper 2 GB address space leaving only 2 GB available for RAM.

If the video system requires RAM for it's own purposes the value available to Windows will be further reduced.

A 64 bit OS has a much larger physical address space so almost all of RAM will normally be available to the system. With some hardware configurations will not be the case but I will not deal with that here.

Edit: In your case adding 1 GB RAM for a total of 4 GB with 1 GB reserved would leave about 3 GB for Windows. System reserved space is independent of how much RAM you have.

 

[gupgup]

Thanks for the detailed explanation. Ok, as I understand is, I have a 4gb cap on Physical Address Space:

4gb - Max physical Address Space
3gb - Installed Ram on my system
1gb - "Hardware Reserved" Address space on my system (as reported by Resource Monitor)
Remainder: 2GB usable space

But if I have, 4gb installed shouldn't the Math be

4gb - Max physical Address Space
4gb - Installed Ram on my system
1gb - "Hardware Reserved" Address space on my system (as reported by Resource Monitor)
Remainder: 3GB usable space ??

I am assuming the "Hardware Reserved" number reported on the Resource Monitor includes all the address space that is reserved by the hardware in the system, including graphics cards

Or does the dedicated, discreet graphics card memory on my two ATI HD 4350 cards (512 MB each) take up an another 1gig of address space, IN ADDITION to the "Hardware Reserved," leaving only 2gbs of usable?

 

[gupgup]

Quote: "Edit: In your case adding 1 GB RAM for a total of 4 GB with 1 GB reserved would leave about 3 GB for Windows. System reserved space is independent of how much RAM you have."

Just saw this. So, I guess then this would agree with my aforementioned understanding?

 

[greenbrucelee]

you will never use more than 2GB ram unless your into video editing and CAD.

However you are running dual channel memory but your only running in single channel mode because you have three sticks instead of 2 or 4. If your system was not using some ram for the video card you would actually see a performance increase by only having 2GB installed but since it is you should get the extra stick so you have 4GB and then you will run in dual channel.

Make sure all sticks are the same size,speed,voltage and make. It would actually be better if you only had two sticks installed and both were 2GB each.

 

[gupgup]

Hi greenbrucelee. Thanks for your suggestions.

I currently have two sticks (2gb & 1gb), so I'm assuming it's running in Dual channel. And to make the total 4gbs, I would replace the 1gb stick with a 2gb stick, so I assume it will still run in Dual channel mode.

 

[greenbrucelee]

they should be the same size i.e 2x2GB do yes replace the 1GB dimm with a 2GB of the same make,speed and voltage as the other 2GB dimm.

Sometimes buying seperate sticks can cause issues buying a kit is safer option.

 

[Fjandr]

This article will give you an in-depth explanation of how Windows uses memory, and there is a section on the 4GB limit and how device memory impacts total available memory.

In short though, yes, your video cards reduce available system RAM on a 32-bit system.

 

[gupgup]

Thanks for the article, Fjandr! Very informative.

My basic concern is that given my current "Hardware Reserved" address space of 1gb, if I have 4gb installed, I'll be able to get more than the 2gb usable I'm seeing right now.

 

[LMiller7]

Hardware reserved memory is address space reserved for other things, plus RAM that is needed for the video system. For practical purposes there is no difference. It is RAM that is not available to Windows.

Dedicated video memory is not accessible by the CPU and does not appear in the physical address space. It is private to the video hardware for it's exclusive use. Video drivers know about it but can't access it directly. Windows memory manager doesn't even know it exists.

I don't believe such exists at the present time but it is possible that some future video card might itself have over 4 GB of dedicated RAM.

Edit: If you add 2 GB RAM to your current 2 GB you should have about 3 GB available to Windows. And it will be able to use it. The memory graph may never show 3 GB in use but it is being put to good use. Not shown in the graph is the "Standby" memory. I will not describe this in detail but it is something like a cache. In many cases 50% or more of system memory will be on the standby list. A large value is very important for good performance. Only memory labeled as "Free" is unused. In general the lower this number the better. The ideal would be zero free memory at all times but we are not there yet.

 

[gupgup]

Thanks, LMiller7.

In light of what you've said, hopefully, I'll have 3gb of usable memory once I have 4gb total installed! I'm assuming the "Hardware Reserved" part is going to stay constant, as I'm not making any hardware changes to my system.

I've ordered a 2gb stick, and will install it over the weekend. I'll report back with the results

 

[gupgup]

I just put the extra 2GB of ram in, and guess what? The "Hardware Reserved" portion in Resource monitor now shows 2048MB!!! ??? I tried to switch the memory sticks in the black slots (initially, they were on white slots), but got the same result. In every combination, only 2gb of usable memory was reported. Curiously, when I just left one 2gb stick in and rebooted, the "Hardware Reserved" part in Resource Monitor only reported 2MB as being reserved. I have NO IDEA what's going on here!

 

[gupgup]

BTW, all 4gb are recognized. For whatever reason, - It locks up 2048MB as "hardware reserved" with 2gb + 2gb sticks - Locks up 1024MB as "hardware reserved" with 2 gb + 1 gb sticks - Locks up only 2MB as "hardware reserved" with one 2gb stick I'm at a complete loss.

 

[Fjandr]

Check the BIOS settings to see if there's an option to enable memory remapping.

 

[gupgup]

I just checked the Dell Bios and I see no such settings. I even updated the BIOS to the latest version, and don't see any settings for memory remapping