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I just installed two 4GB DIMMs (8GB in total) into my laptop (Lenovo T510). Previously, I had two 2GB DIMMs (4GB in total).

Anyway, looking at Windows 7's system information applet, I see the following:


This is rather strange because when I had 4GB in total, nothing was "lost".
The loss is no big deal, but I'm curious to find out what has reserved it.

How can I check which devices are responsible for this?

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up vote 4 down vote accepted

Most laptops have integrated video cards that use a portion of your system memory as memory for the video card. Your particular laptop is available with an integrated or discrete video adapter, so you'll have to check the specifications of your precise build to be certain. However, there are some settings in Windows or your BIOS that could cause this.

According to Microsoft, the "usable memory" calculation on the System control panel is inaccurate, so take whatever it says with a grain of salt. You can double-check whether this memory is actually being reserved by hardware using the Resource Monitor application included with Windows 7.

There is more information on this calculation, the BIOS and Windows settings you can change that might be affecting it, and the Resource Monitor application in this article from the Microsoft Knowledge Base.

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Thanks. Yeah, I forgot to mention that my laptop does not have integrated video. I've also confirmed via resource monitor that there is some memory put aside as seen here. Also, here is where you can see the address ranges for your devices. Guess I'll get out my calculator... :) – CAholdem Mar 6 '11 at 2:13

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