You’ll then be given a screen that displays your processor speed and how much RAM is installed.

You might have wondered how to get more RAM on your mac. You can replace it yourself, but you need to be careful where you buy it from.

In case you haven’t yet realised,  Apple Memory is different to normal PC RAM,  so if you go to a cheap PC shop or ebay and buy some memory it probably won’t work in your Apple computer. Here’s a reliable place I have found to buy RAM that works well in your Macintosh.It’s not that you need ‘Apple’ memory,  but you do need high quality RAM with certain specifications that are not obvious so you need to buy from someone who knows the differences. You can buy RAM that is the right speed (eg 667 MhZ DDR2 FB-DIMM etc) but it still won’t work.

After much trial I have found a very reliable source of Mac RAM to be crucial. (Crucial is the name of the shop!)

Check them out at Crucial.com They even have a little program here that you can download and it works out what computer you have and then pops you onto their webpage on the page showing the memory you need to buy!

Their prices are very good too. For example 1Gig of RAM For my 1.67 Ghz PowerBook was only $49 US and shipping to Australia was only $25.

1. Go to your Applications/Utilities folder. (Click on your desktop so that the finder is active then hold down Apple-Shift-U, this will open your ‘utilities folder.)
2. Open ‘Activity Monitor’ – it will probably be the top-most application in the Utilities Folder.
3. Press Apple-1 to make sure that the main window of Utility Monitor is open.
4. Click on the ‘System Memory’ tab at the bottom of the window. This will display a little pie graph of how much memory you are currently using. It will look something like this:

There are two important items to take note of ‘Free:’ and ‘Page outs:’

Free tells you how much free memory you currently have available to use –  the higher the better.  If you have no free memory you should get more RAM.

A Page out  means your computer has run out of memory and had to use some of the Hard Disk instead of RAM. (This is the equivalent of your brain being too full so you have to write your thoughts down on paper to free up some headspace) This DRAMATICALLY slows down your computer.

To quote from Apple:

Moving data from physical memory to disk is called paging out (or swapping out); moving data from disk to physical memory is called paging in (or swapping in)… Extended periods of paging activity reduce performance significantly; such activity is sometimes called disk thrashing.

Tip: Page outs occur when your Mac has to write information from RAM to the hard drive (because RAM is full).  Adding more RAM may reduce page outs.

Some Examples:

Here's a mac with plenty of RAM (12G) - lots of Free RAM (green) and zero Page outs.

Here's a mac with just enough RAM (8G) - a relatively little Page out Count (339MB) and some free memory (green).

Here's a Mac that needs more RAM (it only has 640M!) - note the High Page Out Count (1010524) even though it currently has some 'free' RAM.

This Mac definitely needs some more RAM! Practically no free memory AND High Page-out Count. (1GB!) Performance will be suffering badly. I would add at least another 4G Ram, maybe 8G more to bring it up to 12G.

In OSX Leopard rather than giving a ‘count’ of page in and page outs, it gives a size in GB  of the amount of RAM that has been paged in or out. The numbers are smaller but the same principals apply.

In OSX Lion there is a new entry called ‘Swap Used’. (See the last picture above). This  is a count of how much Disk Space your computer is using as RAM and it’s a good rough estimate of the minimum amount of  extra RAM you need. Eg If your Swap used is 4G then get AT LEAST 4G more RAM.

Where to buy more RAM.

If you do need more memory  I recommend buying it from Crucial. They have good prices and reliable RAM. I’m in Australia and it usually arrives in about a week. They have a great memory lookup tool for all Apple Computers where you choose your model and it shows you exactly what memory you need.  The memory chooser tool looks like this:

First choose ‘Apple’ where it says ‘Choose Manufacturer’

Secondly select your mac when it says ‘select product line’ (e.g. iMac or Macbook etc)

Finally select the exact model (e.g. Early 2011 i7 27″ iMac”)

It will then show you the options you can buy.

Click here to go to the Crucial memory website.