My Windows Vista will only recognize half of the memory

by georgerommel Jul 14, 2009 6:07AM PDT

I have a Toshiba laptop X205-Sli1. Originally, it has two 1G memory chips. Later, I installed two 2G memory chips in it hoping to have a total of 4G memory. However, my windows only recognizes 3G of the memory. When I open my bios, it indicates that I have a 4G in the memory. Therefore, I think there is something wrong with my windows vista. Any ideas? Thank you very much!!!

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That's by design.

by Kees Bakker Jul 14, 2009 6:10AM PDT

Nothing wrong, nothing broken. That's the way it is. And I think it's even so in Windows 7.

Luckily, for most applications and job mixes, 3 GB is sufficient.

Kees

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That sounds more like

by Jimmy Greystone Jul 14, 2009 8:44AM PDT

That sounds more like 3/4 of the memory, not 1/2. But as has been said, there is nothing wrong here. Way back when Intel introduced the 386 CPU, the first 32-bit CPU in the x86 line, it was well known that the maximum addressable memory space was 4GB, but due to protected mode operations (that keeps one app from overwriting memory used by other apps, creating General Protection Faults (GPF) errors that Windows 3.x veterans probably have many unfond memories of) you end up losing about 0.5GB.

This issue has been known for about 20 years, so if you must waste time on pointless recriminations, then most of the blame would lay with Microsoft for failing to properly educate its userbase of this issue. Also for computer makers who were all too happy to sell people systems with 4GB+ of RAM with a 32-bit OS, and never once utter a peep about this issue.

You can either accept the loss of about 0.5GB of your total RAM, or you can install a 64-bit OS. Your choice.

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by georgerommel Jul 14, 2009 9:08AM PDT

that's very interesting. you are saying my computer itself is running with 4G memory, but the system only indicates 3/4 becaus it wants to protect the computer from overuse the memory. Therefore, the rest 1/4 of the memory is like a reserve for the system or something?

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Just FYI

by r. proffitt Forum moderator Jul 14, 2009 9:21AM PDT

You may be ignoring the millions of posts about this. There is no mystery here.

Hint. Tell me the values you can represent with a signed 32 bit integer. It is much less than 4GB

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by Jimmy Greystone Jul 14, 2009 9:33AM PDT

No, not quite. Protected mode means that say Internet Explorer can't accidentally write data for some new web page you loaded into an area of RAM that's holding the Word document you're working on as well.

Back in the "dark days" of 16-bit operating systems, this sort of thing would happen ALL THE TIME. You'd be running along in Windows 3.1, then out of nowhere a General Protection Fault (GPF) error would pop up and if it didn't cause an app to crash, it rarely worked properly after that until you restarted it. Most people don't even know about GPF errors, or have long since forgotten about them since they've pretty much disappeared.

But the deeper explanation as to why this requires that you lose access to about 0.5GB of RAM won't really make any sense unless you have some programming experience with lower level languages like C\C++. Let's just leave it at it's something of a buffer to keep things flowing smoothly.

My Windows Vista will only recognize half of the memory

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