I understand the concept of memory, and how it is installed. I also understand the fact that computers "max out" in memory. My question is why? Is it because due to certain motherboards the processor can only hold so much memory because of its speed? Say if I wanted to add 1 gb of memory to a compaq presario 3000. would I be able to add the stick of memory, but it would fry the motherboard? Or is it even possible to fit the stick of memory into the slot on that certain motherboard? Please can anyone enlighten me?


The Beginner

Your're on the right track, the width of the CPU’s address bus determines the maximum amount of RAM that can be used. If you want to read more about this go here.

The other determining factor is the OS, W2k and XP have a limit of 4GB, but with Vista this gets a little bit complicated.

* 32-bit versions of Windows Vista Home Basic, Home Premium, Business, Enterprise, and Ultimate: 4GB
* 32-bit Windows Vista Starter: 1GB
* 64-bit versions of Windows Vista Home Basic: 8GB
* 64-bit versions of Windows Vista Home Premium: 16GB
* 64-bit versions of Windows Vista Business, Enterprise, and Ultimate: 128GB

Different modules have different numbers of pins, PC133 has 168 pins, PC2100 has 184, and so on. This makes it impossible to install the wrong type of RAM.

The following is an excerpt form this article.
Motherboard chipsets not only control the maximum amount of RAM you can insert, but the cache area as well. The Cache area is the first X megs of RAM that the L2 cache can retrieve information from for relaying to the CPU. If there is more RAM on board than the maximum cache area can handle, all memory after the limit must be accessed directly by the CPU, which can involve performance hits depending on application.

I hope this helps.

Thats exactly what I was looking for. Thanks dcc!