I upgraded the memory on my Dell laptop. The laptop had advertised, and Dell had confirmed, that the laptop could use up to 4GB, this limitation imposed by the “memory density”. The laptop has two DDR2 slots, each capable of using a 2GB memory card.
A BIOS blocks off some amount of the available addressing for its own uses. While in theory a 32 bit machine is capable of addressing 2
But my laptop has a T7200, a 64-bit cpu, so with a 64-bit OS, I should be able to address all 4G, right?
No, actually. It turns out the computer has something called a "chipset". I'm not exactly sure what a "chipset" does, but mine is an Intel 945, which is 32 bits. This turned out to be the limiting factor.
Why would Dell use a 32-bit chipset with a 64-bit CPU?
Parenthetically, I have become less enamored with Windows 7:
I can't get hibernation to work. This is a fairly common problem. Most users claim to have fixed it with the right combination of power management settings, but I'm not one of them.
The multimedia playback stutters. Not often, and not for long: only a few times per DVD perhaps, but still: XP never does it.
It's a memory hog. Windows 7 requires over twice the memory at startup as XP.