Rules for adding/upgrading RAM

I need to upgrade RAM on my machine.

I've done this before, but it was ages ago. There were rules or guidelines then as to what could and couldn't be done (some rather obvious) :

• All RAM to be of the same type
• When adding two sticks of RAM to parallel (twinned?) slots, both need to be of the same capacity and preferably of the same manufacturer.

etc..

There are lots more types of RAMs and processors now, and I'm not sure what I need to be aware of when I buy new RAM for my machine.

So my question is, what are the rules you know of that I need to follow while upgrading RAM ? Are there dependencies between processor and RAM type, or motherboard and RAM ? Do you know of any downsides to having 4GB RAM on a machine running a 32-bit OS, besides it not recognising the full capacity ? What are the chances I'll be able to use this RAM when I upgrade to a newer CPU/motherboard in future ?

Solution 1:

When you look at the Crucial references on my answer to your other question about memory,
you'll get an idea on some of the questions here.

To understand the double channel Twinned performance, have a look at my answer to,
Should I be worrying about Single Channel and Double Channel for my RAM?.
For matching requirements of good dual channel performance,
manufacturers usually pack matched devices into a 'kit'.
That is a bit more than the same manufacturer.

Regarding upgrade to another system and moving the new RAM sticks there.
I guess, it is important to note that you are using SODIMM on a Dell Inspiron laptop.
You will be limited to motherboards that take SODIMM modules (at the least).

Solution 2:

I've found the easiest way to be sure you're buying the right thing, is to simply use automated tools to do it for you, such as here.

I've never heard of any issue using 4GB of RAM on a 32 bit system (and i've never had any issues), at least for windows.

As for compatibility with a motherboard you may buy in the future, it'd probably be best to pick your motherboard at the time to fit the ram, although if you are buying a new motherboard in the future, it's probably for a new processor too and ram is fairly cheap if worst comes to worst.

Somebody else should be able to give more specific answers (look at "nik"s), but i hope this pushes you in the right direction. Good luck.