Installing RAM

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Hopefully, you have visited the Buying RAM page of this wiki and are now here to continue your adventure with installing RAM.



Installing RAM is pretty simple in Macs, although you need to take some precautions to avoid unintentional damage (like static discharge, for example). Apple provides a Do-It-Yourself guide to upgrade or repair your Apple product at Do-It-Yourself Parts and Service. Select the product you're interested in from the drop down list and read through the detailed instructions. Also, on the inside coverings of many Macs are graphical instructions on how to install the RAM. The iMac G4 is a good example of this- after the bottom cover has been removed, there are instructions on how to add RAM.

If you'd like to see videos of upgrades, just to make sure you're doing the right thing, you could also check the OWC's upgrade videos section that has some detailed (and yet small) videos. You can also reach this page from OWC's home page - select the 'Tech Center' link and proceed from there. Upgrade instructions for many Powerbooks, iBooks and older Macs can be found at

Machine Specific Tips

Any machine with screws to remove

Get the right size Phillips screwdriver to fit the screw tightly, use no other. Be serious about bearing down on the driver to hold the tip in as you make the first turn. Do not let the driver ride up and out of the screw, otherwise you can ruin the screw. Don't be timid.

Intel iMac and MacBook SODIMMs

When you push the RAM into the socket, you cannot see what you are doing. First, make sure the slot in the RAM connector edge matches the key in the socket (or the diagram next to the socket). The RAM is a straight push in - the RAM will go in about 1 inch and stop. It is not installed yet. You need to get both thumbs on the RAM and push it in 1/8" (2mm) more to get the pins fully seated into the contacts. This is important to make sure the memory is not ill contacted - a significant proportion of RAM 'failure' on these machines is actually a failure to push the module in hard enough.

PowerBook and iBook and MacBook SODIMMs

These machines use flat sockets that you have to angle the RAM into. First, make sure the slot in the RAM connector edge matches the key in the socket. Hold the RAM at approximately a 30 - 45 degree angle, then push the connector edge into the socket. Now, with both thumbs on the long edge of the RAM, push in with modest force, to make sure the pins are fully seated into the socket contacts. This must be done while the RAM is still up on the angle. Then, lay the RAM down to the flat position; the clips will click in on either side (however the clips clicking is not an indication that the pins are properly seated). Inspect the RAM at the socket; there should be none or very few of the gold pin contacts remaining visible, and the RAM should be perfectly parallel with the socket. If it is angled, or you can see more than 1/16" (1 mm) of contacts, take it right out and do it again. You cannot push it successfully in while it is flat.

Mac Pro FB-DIMMs

The Mac Pro Xeon machines use FB-DIMMs. They are installed in pairs. The machine has 2 riser cards that take the RAM, each card has 4 sockets. You populate the RAM in pairs, with the largest RAM in the numerically lowest slots -- in this order:

A1 A2

B1 B2

A3 A4

B3 B4

The sockets 3 and 4 have a higher latency than sockets 1 and 2, so put your largest RAM in the 1 and 2 sockets.

There is a small speed benefit to installing 4 identical modules across both risers: A1 A2 B1 B2 which permits 256-bit access mode. However, do not buy smaller RAM modules just to match an existing pair.

There is a diagram on the inside of 2007 Mac Pros to help identify installation order. Newer Mac Pros have a diagram inside directing you to see the User Manual for installation instructions, instead.

The 2008 Penryn MacPros deliver with RAM in A1 B1. This must be changed if you are adding RAM. If you are adding one pair, put the new RAM in A1 A2 and relocate the Apple RAM to B1 B2.

G5 iMacs

Do not install RAM with heatspreaders or heatsinks installed. They do not physically fit and you will break the socket on the logic board if you try.

G4 iMac

The user accessible SODIMM socket on the bottom is easy to replace, just remove the round metal plate on the bottom of the machine. The internal DIMM socket however requires disassembly of the chassis out of the 'dome' and is best handled by a technician with the correct instructions for disassembly and reassembly. If it is not done correctly, the machine will be prone to overheating and may be permanently damaged.

After Installation

The last step before enjoying your new memory is to thoroughly test it. If errors come up, you'll want to know this so you can return the memory without risking data corruption. See the Testing RAM guide for details.