Dell D820 4GB Memory Upgrade Problem
October 6th, 2009 Category: GeneralI decided to upgrade my Dell Latitude D820 notebook from 2GB to 4GB memory so I went into a store, purchased 4 GB RAM and put them into my notebook. By the way, Windows 7 Ultimate is running on this notebook since a few weeks very well. What happened?
First boot
Screen stays blank and the three LED’s on the keyboard were blinking.
Second boot
Removed 2GB and booted again, everything correct.
Third boot
Put 2GB back again and notebook booted with the message:
The amount of system memory has changed.
If you did not change your memory…
To resolve this issue, try to reseat the memory.
Huuuu what? Never seen such a message before in my “IT-life”. Tried several things, rebooted several times. Result was the same. While goggling on the desktop I did not watch the notebook. When I come back to the notebook an additional message appeared:
Strike the F1 key to continue, F2 to run the setup utility
Press F5 to run onboard diagnostics.
So I pressed F5 for the diagnostics just to see what will happen. After running the diagnostics the notebook booted fine and recognized the new memory.
If you see this strange message also after you upgrade your memory just wait a little bit until the next message appears. Very strange behavior, indeed. But now it works, memory for the masses 
One issue is that you will only be able to use about 3.3GB of your 4.0GB, for details check this blog entry:
Missing memory
My Windows 7 32-bit installation reports 4.00GB installed, but only 3.25GB are usable. The reason why Windows is not able to access all the 4GB is kind of hardware restriction. For details refer to the Microsoft Help and Support article:
According to Microsoft this also affects 64-bit editions of Windows Operating Systems, sounds reasonable since it’s a hardware restriction.