Did I just waste my money upgrading to 4GB RAM on a M65 precision?

So I bought a M65 precision a few years ago (3-4)

Now that a good windows OS 64bit is available, I decided to to upgrade my ram from 2gb to the maximum 4gb.

After seeing that my computer recognizes 4GB but is only using 3GB I got pissed off.

After some research I found this link:
http://www.artima.com/forums/flat.jsp?forum=152&thread=158081

"So you pay a really huge premium (compared with 2Gb RAM) to get 4Gb of RAM ... and so how much memory do you expect the BIOS to make available to the OS. For a Dell M65 the answer is just 3.071Gb.

Response from Dell ...

The processor only has 32 address lines, limiting it to an addressing map of 4 gigabytes.

The chipset, PCI devices, PCI express region, and video cards use some of this map, and the BIOS correctly reports this range as unavailable to the operating system. If the user installs 4 GB of physical memory, then the processor has no way to address the memory that overlaps with these regions, already in use. The chipset directs memory access to the appropriate device rather than sending it to random access memory (RAM).

On Dell's new line of desktops, PCI express uses 500 megabytes (MB) in the map; integrated video takes 256 MB right below PCI express, leaving 3.25 GB of memory available to the operating system via RAM. In some cases, less RAM is available depending on what other add-in cards are installed.

Therefore there is no hardware or software fault with the system. This is working as designed. "

So did I just waste my money?

 

The answer to your problem is in head.

Please tell us the details specification of your system, with EXACT CPU model, as well as the full name of the operating system used.

Assuming your CPU is a 64-bit one, and that the motherboard supports 4GB of RAM, then you need a 64-bit Operating System to use your full 4GB of RAM. Using a 32-bit Operating System will only allow you to ADDRESS up to ~3 to 3.7GB of RAM depending on your system configuration. This limitation is due in part by your CPU architecture if it's a 32-bit only CPU, or a 64+-bit CPU locked down to a 32-bit CPU by a 32-bit Operating System.

 

Sorry, I left that part out by mistake

CPU is a T7200

Im using windows 7, 64 bit, check out this screen shot

 

That post is from 2006, it's outdated. At the time, 1GB sticks were reasonably priced, and 2GB sticks were insanely expensive (more than 5 times the price, is my guess).
You have the same disparity at 2GB-4GB sticks today, with 2GB sticks at $35, and 4GB sticks at $300+.
At the time, it would be extremely expensive, and not worth the extra upgrade, unless you REALLY needed it, and I'd say the same thing now for 4GB sticks. But 2GB sticks are decently priced, and are in no way "wasting" your money.

 

Well I was just curious if I should return one stick to dell and get some money back plus a 1x1GB stick....That way I would have 3gb of ram

or would I lose the performance advantages of dual channel memory?

 

I believe that the loss of 1GB is due to the video card + sound card that reserve your system RAM. If you remove your 4GB setup and put 2GB, do you have 1GB or 1.5GB usable?

Also see with Dell, if your laptop motherboard supports 4GB, it could be that the motherboard has a 3GB limit because it was not designed for high amount of memory.

Losing dual-channel will degrade system performance, but gain few minutes to battery life. How much performance loss? I have no idea, I never ran a system without dual channel.

 

I can't remember it ever saying I had less than 2gb usable when i had 2gb in there

Im not sure, hopefully someone else could chime in with 2 or 3 gb in their system

 

The loss of additional space is only relevant when you get to the maximum amount of RAM - with 32-bit you have at most 4 GB of *addressable* space, but this includes that used by graphics and some other system functions. So if you had a 1 GB graphics card, the most memory that would be used was 3GB (a little less, actually), since 1GB of the address space would go to that. But I'm guessing you don't have that.

Unless you just bought one of the sticks, you couldn't return it to Dell, and if you did, you should consider returning them both and buying from New Egg instead, as it's likely cheaper (check, first). But it's nice to have it in case you switch to 64-bit (you should), or use Linux, which can handle it better.

 

The chipset you have on the computer can only address 4GB of space. All the devices in the system use some of that addressing space, including the video card. RAM gets whatever addresses are left after all the devices get their addresses.

It is called Memory Mapped I/O, read up on it through Wikipedia and Google if you want to learn a little about it.

Newer chipsets support up to 8GB of RAM in laptops (around 6.8GB-7GB RAM limit though), while even newer Core i7 computers can support up to 24GB. A few workstation laptops out now can support more than 16GB, I think the newer Dell Precision notebooks support up to 16GB...

 

Does this mean, for example, If I was only running 2GB physical, all the devices in the system would still be using some of that addressing space? So I would really only be using about 1GB RAM? Like wise for 3GB?