2 GB of Memory? Huh?

MonCapitan2002 · #1 11-03-2006, 05:56 PM

Since the debacle with Starforce, I have come to the reluctant realisation that I need a new drive. So while replacing the drive, I decided to upgrade my computer's memory as well as add a hard drive (only the memory arrived, the other components experienced a delay in coming to me).

Now I bought two 1 GB modules for my computer. I removed my old 512 MB modules and replaced them with the 1 GB ones. Once that was done, I installed the 512 MB modules in my computer's third and fourth DIMM slots. Now I turned on the computer and booted it up. When I went to check the system information, the OS only recognised two gigabytes of RAM. Three gigabytes are installed. I checked the BIOS and it recognises three gigabytes of installed RAM.

I have read that XP can recognise up to four gigabytes of RAM so why is my OS only recognising two?

seebs · #2 11-03-2006, 06:57 PM

Don't know. Are they all compatible and same-type? I have had XP using 3GB of memory successfully in the past, so it's at least possible.

MonCapitan2002 · #3 11-03-2006, 06:59 PM

Same type meaning? I believe both are dual channel. The only difference is in the size of the modules. Their speed is the same.

Zehava · #4 11-03-2006, 07:02 PM

Took me awhile to track down any info but this is what I came up with.

While 32-bit Windows XP can address up to 4GB of memory, only 2GB is addressable by applications. See Memory Limits for Windows Releases

Memory above 2GB is reserved for the OS. If you have Windows XP Professional SP2 or better you can increase that limit to 3GB, but that entails modifying the BOOT.INI file, using the /3GB switch. Yes this link is from HP but it is not specific to HP computers.

Modifying the BOOT.INI file is not something to be done lightly and can easily leave you with the non-bootable system.

So for all intents and purposes Windows XP 32-bit is limited to 2GB of memory. Will this stop the OS from displaying that there is more than 2GB installed? I don't know.

seebs · #5 11-03-2006, 07:36 PM

Huh. I had a system that said it had 3GB installed.

I think the link is confusing "per-application limit" with "memory available to system". Lots of systems have smaller limits for each individual program.

Zehava · #6 11-03-2006, 08:55 PM

Quote:

Originally Posted by seebs

Huh. I had a system that said it had 3GB installed.

I think the link is confusing "per-application limit" with "memory available to system". Lots of systems have smaller limits for each individual program.

Yep you are right.

Physical Memory limit is 4GB for XP. The 2GB limit is per 32-bit process.

Well fuck. After looking further and reading several boards the whole issue is as clear as mud. I'm going to bow out now saying "fuck if I know"

Stormlight · #7 11-03-2006, 09:08 PM

Quote:

Originally Posted by seebs

Don't know. Are they all compatible and same-type? I have had XP using 3GB of memory successfully in the past, so it's at least possible.

The main problem is often that the motherboard requires that the memory banks are the same modules (same size for example or same brand). Do you still have your motherboard docs? Check it out.

Also, try to reposition the 4 modules: switch them around and see if it works. Next remove all but one and try if it works. If it does, remove it and try with another.

But quite honestly I assume that the problem lies with the fact that you mix 1 Gb with 512 Mb modules.

Adam · #8 11-03-2006, 09:23 PM

Yah, the Windows limit is the amount of RAM addressable by a single process, not the amount available to the system as a whole.

I think Stormlight has it right...more than likely, your mobo won't recognize non-identically sized sticks.

MonCapitan2002 · #9 11-03-2006, 09:32 PM

The BIOS is recognising the 3 GB of memory. It is XP that isn't recognising it. From what I understand, the memory is installed in pairs. Slot 1 and 2 is a matched pair (both 1 GB). Slot 3 and 4 is also a matched pair (512 MB). When I open the BIOS, the system registers three gigabytes of memory installed on the motherboard. XP is only showing 2 GB of memory.

Corona688 · #10 11-03-2006, 11:32 PM

You could try updating your chipset drivers.

Stormlight · #11 11-04-2006, 06:55 AM

Quote:

Originally Posted by MonCapitan2002

The BIOS is recognising the 3 GB of memory. It is XP that isn't recognising it. From what I understand, the memory is installed in pairs. Slot 1 and 2 is a matched pair (both 1 GB). Slot 3 and 4 is also a matched pair (512 MB). When I open the BIOS, the system registers three gigabytes of memory installed on the motherboard. XP is only showing 2 GB of memory.

Did you try running the Windows Memory Diagnostic Tool?

BracesForImpact · #12 11-04-2006, 08:00 AM

Where did you get your PC? Have you ever had it to the shop for repairs? The reason I ask is that someone could have messed with your BIOS so that windows is defaulting memory somewhere, a device or PCI card, for example. Try setting your BIOS back to default, or updating it.

Other than that, Stormlight gave good advice, some motherboards are touchy buggers.

seebs · #13 11-04-2006, 09:04 AM

Pairs like that certainly should work; as I said, I had a machine with the exact same setup for a while.

Sounds like Windows is screwed up. If you can take the hit, do a fresh install -- ideally on a new drive, and just copy individual things over from the old one.

MonCapitan2002 · #14 11-04-2006, 05:58 PM

It might be the model of the PC I have. When I got it, the manufacturer said the maximum amount of memory it can have when using XP 32 bit was 2 GB. I thought it was an error on the manufacturer's part. I have an XPS 600. I am the only one who uses it and the only one who has been into the BIOS.