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My girlfriend bought a laptop last week. It's a core 2 duo with 4 GB We installed vista 64bit, and one of the first things we did was right click on "My computer" to see gthe properties. Immediately we noticed something strange about her RAM, the line said: Installed memory (RAM): 4,00 GB (3,68 GB usable)

I told her not to worry, thinking it must be something about the laptop hardware (considering her vista installation came from the same DVD as mine, and I never noticed anything like that on my 4 GB desktop). One hour ago, it got worse. We looked at Properties again, and it now says: Installed memory (RAM): 4,00 GB (2,98 GB usable)

What does that mean? Are those 1,02 GB missing or being used by the system?

EDIT: There is a possibility that the sytem information is wrong. I just noticed that it reports an intel T6500 processor, when it's actually a T6400. How can I find out how much RAM is really available to the system?

EDIT2: Checking the resource monitors, it says 1003 MB are reserved for the hardware. Is that good or bad? Thanks

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87% accept rate
Are you really sure that you've installed the 64-bits version? – Wim ten Brink Oct 11 '09 at 21:52
Yes, absolutely. It is the same version I installed in my desktop, and I never had this problem. – Bruce Connor Oct 11 '09 at 22:10
If the incorrect CPU is reported, it could be either the reporting utility is old, or the BIOS needs to be upgraded. – kmarsh Oct 13 '09 at 12:32
could it be that I'v got the wrong driver installed? – Bruce Connor Oct 13 '09 at 19:22
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7 Answers

up vote 11 down vote accepted

Two possible reasons:

  1. the video card sharing RAM (using motherboard RAM instead of having its own, or using motherboard RAM to supplement its own)
  2. the motherboard chipset does not support remapping (the PCI architecture traditionally "owns" a chunk of the top Gb of the bottom 4Gb of physical memory, the remapping moves this above where your RAM is actually sitting so the two areas don't overlap). This is common with chipsets that only support 4Gb of physical RAM in total.
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Some more about chipset limits at this thread: superuser.com/questions/35731/… – Chris_K Oct 11 '09 at 23:21
Also, don't forget about the 3 and change Gb limit on 32 bit machines. – tvanover Nov 9 '09 at 18:30
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up vote 14 down vote

The usual reason for this is shared ram with video.

Check in the BIOS and see if you can see / set how much memory the on board video uses - however I doubt it will be as much as 1GB and not sure where the rest can be (unless you have any sort of weird memdisk like utility)

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Checking the resource monitors, it says 1003 MB are reserved for the hardware. That's a good thing right? – Bruce Connor Oct 12 '09 at 21:01
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up vote 2 down vote

How can I find out how much RAM is really available to the system?

You can use CPU-Z

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up vote 1 down vote

Start > Run > Type MSCONFIG and click OK

Boot > Advanced Options

check wether maximum memory is capped.

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The box is checked and it's set to 0. – Bruce Connor Oct 12 '09 at 0:59
IF the box is checked then set it to the maximum available memory (i.e. 4096) ... or CLEAR the box. – Molly7244 Oct 13 '09 at 17:05
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up vote 1 down vote

BIOS shadowing, Video addressable area, and other memory mapped devices reserves memory between 640K and 1M and between 15G and 16G. The BIOS itself may remap (and therefor reserve) system memory into these areas for its own use.

In the end the O/S never gets 100% of the memory installed, but that doesn't mean it isn't getting used.

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Well, as long as it's being used by the system, it's really ok. I was worried that it might not be used due to some bug or hardware deffects. – Bruce Connor Oct 12 '09 at 20:59
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up vote 1 down vote

I found a great explanation for this problem -- hardware is memory mapped -- at the following URL:

http://www.codinghorror.com/blog/archives/000811.html

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Really informartive, thanks! – Bruce Connor Oct 13 '09 at 0:43
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up vote 0 down vote

I figured it out. After tinkering with it for a few hours, it turns out that the "Memory Reamp" needs to be enabled. On some Asus mobo's and a few other brands, when Win 7 is installed it recognizes that this problem. The problem was there all along and people just didn't know it until Win 7 was installed and pointed it out as a precursor to a BIOS problem that had been there the whole time. 1 Enter BIOS 2 Advanced 3 Chipset Settings 4 Enable Memory Reamp Feature 5 Exit and Save 6 You’re Done!

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