Home > Mac, mods, Technology > Upgrading iMac 15″ flat panel (iLamp) Hard Disk, DVD Drive and Memory to the full 1GB

Upgrading iMac 15″ flat panel (iLamp) Hard Disk, DVD Drive and Memory to the full 1GB

I was thrilled to see just how well Leopard ran on my new 700MHz iMac 15″ flat panel LCD with the user upgradable RAM increased to 640MB and the stock 40GB hard disk.

So, I am really looking forward to seeing the performance and how the thing performs with a full 1GB of RAM (considered minimum for OS X 10.5 Leopard to run smoothly. I suspect that it will be 100% usable, not a “poor” or “barely ok”, but a full on “nice” or at least, “not too shabby.” 

Firstly, You will need a nice set of tools to get inside the iMac, it’s a bit of a fiend to open, along the lines of the Mac Mini, but with more screws! Not impossible, but not trivial.

First Up, make sure you have all the components you need

  • 3.5″ PATA (Ultra ATA 66) HDD. There is no space for a SATA-PATA converter, so get the real deal.
  • A Mac Compatible DVD Writer (preferably one with iDVD support).

NOTE: The DVD writer should be less than 19.5cm deep since that’s the size of the drive that’s in there. The tray bezel should also be removable.

  • 512MB, PC133 (133MHz) 168 pin DIMM.
  • 512MB, PC133 (133MHz) 144 pin SO-DIMM 

Before you start make sure that everything is ready:

    I’m shouting this because this is easy to overlook and WILL turn your iMac into a paperweight if you forget it.
  • A set of Torx drivers, a number 10 and a number 15 should do the trick, but don’t quote me on that! Better off having a whole set from 6 to 20.
  • A Plus head screwdriver. I have no idea what size, just look at the screws and be the judge 🙂
  • A wide open, well lit space to work, covered in a soft duvet, pillow or stack of towels.
  • Somewhere to earth yourself or better yet, a grounding strap.
Prepare your iMac for surgery:
  • Unplug your iMac completely.
  • Clean your iMac. Stray dust WILL somehow find a way to scratch your screen at the first opportunity.
  • (optional) You might want to wrap the screen in a soft, clean towel and pin it with safety pins.

 Removing the user accessible parts of the iMac.

  • Unscrew the base screws with the plus-head screwdriver.
  • Remove the RAM and Airport card, if present.
Removing the base
  • Remove Torx bolts holding base together.
Remove base screws
  • Now remove the base, carefully, prising the bottom off. 

Important: Try not to twist or bend the base in relation to the top. Work your hands around the base, gradually easing the base away from the top. At all times, keep the base parallel to the top until it is clear of the connectors.

Pull the base off the iMac
  • Now the base is off, you may, depending on the way your iMac is being supported, need to detach some or all the cables which hold the base to the top. There are six cables, see the diagram below.

Disconnect iMac base

Make sure you can remember where each cable goes. Also, the green earth cable on the left hand side is secured to the top with a Torx bolt that needs to be removed.

Replacing the internally installed (non-user-serviceable) RAM

The RAM slot is visible at the bottom of the above picture and can now be replaced.

Make sure you replace it with a decent, “full-size” (desktop) 168pin 133MHz SDRAM chip. 100MHz chips tend to cause kernel panics, avoid them!

  • Push the two cream coloured tabs out and down and the DIMM should pop up. Pull it out vertically.

Replacing the internal, full sized DIMM

  • Now might be a good time to use an air blower and clean out the RAM slot.
  • When replacing the DIMM with a new one, make sure you push it in vertically, all the way to the bottom. The two cream coloured tabs should automatically pop into place.
  • I’ll repeat the bit above, make sure you push the RAM in vertically, all the way to the bottom. If you don’t you’ll be reopening your case again sooner than you’d like.

Removing the drive assembly.

Next we are going to remove the drive assembly which holds the hard disk drive and the Combo DVD Drive.

  • Remove the copper tape that holds the electromagnetic shielding from the front of the drive and the two bolts shown below.
  • Gently pull the shielding away from the top and put it aside.

Remove iMac EM shielding

  • Now remove the four bolts that hold the drive assembly in place.
  • Make sure there are no cables tethered to the drive assembly. If there are, you will need to cut the cable-ties and release them.
  • Lift the drive assembly away from the top.

Remove iMac drive assembly

  • Once the drive assembly is out, remove the power connectors from both the HDD and DVD.

The data connector is lodged between the two drives and cannot be removed.

The HDD is covered with a sticky backed film, probably an interference reducing tactic. This film will have to be removed before we can remove the HDD from the assembly.

  • Carefully peel off the paper.


Remove sticky paper cover

  •  Remove the eight bolts which hold the hdd

Remove HDD and DVD bolts


  • Lift out the HDD
  • Slide out the DVD drive, connector first (i.e. backwards)
  • Make note as you do so where the fronts and backs of of each drive sit!

Disassembly Complete:

Read the remainder of this post for some critical tips and then work back through this post in reverse if you need to look at the photos.

  • Replace the drives in the assembly, making sure the ATA cable is between the HDD and the DVD drive before tightening anything.

Drive assembly checks:

Before reassembling, confirm the following:

  • HDD is set to Master and the DVD is Slave or as Apple recommends, use Cable Select for both drives – If this is not done, you will find one or both of the drives inaccessible.
  • The drives are aligned properly and are the right way around!
  • The DVD drive fits – Some are deeper than others!
  • Before you screw the drive assembly into place, make sure you have reattached the ATA connector and the power connectors to both drives. Trying to reconnect the cables after bolting the drives in place is a futile waste of time. (Talking from experience!!)
  • Make sure the appropriate wires run behind the drive assembly before the drive assembly is replaced, since routing the wires around the side may interfere when closing the case. 
  • The DVD bezel on the tray is small enough to fit though the white drive flap on the front of the iMac.

You may need to remove the new DVD drive’s whole front plastic panel and/or the plastic bezel on the front of the drive tray.

  • You will need to remove the bezel first: use a pin, piece of stiff wire or a paperclip to poke the little hole at the front of the drive and release the tray. Behind the lip of the tray, there should be a couple of clips holding the bezel to the drive tray.
  • Now, the drive front panel can be removed (usually, depending on your drive). There are typically four to six holes in the metal casing of the drive, near to the front panel, form which protrude short plastic posts. Pushing the posts in with a screwdriver one by one should release the front of the drive.

Reconnecting everything:

The CPU heatsink is connected to a heatpipe which runs along the bottom of the case from the CPU to a junction, which transfers the heat from the CPU into the upper-half of the base to be cooled by the top mounted fan.

iMac Heat Pipe Bottom

  • Scrape of the old heatsink compound and thoroughly clean and polish the post without filing or reducing in any way. You may need acetone or metal polish. A plastic scraper may also help remove the old gunk which may have hardened due to heat.

iMac Heat Pipe Top

  • Do the same for the top part of the junction.
  • Apply a thin, neat coating of heatsink compound (thermal paste) to either one -not both- of the posts.
If you do not clean the junction properly or forget to apply the heatsink compound, your iMac will freeze, crash and perhaps suffer irreparable damage due to the CPU overheating.
  • Now connect all the wires back up. 
  • If necessary, restrain the cables against the side of the drive assembly to prevent from getting trapped when resealing the base.
  • Align the two halves of the case.
  • Ease the base on, making sure the rear connector is fitting snugly before tightening any bolts.
Do not attempt to run the iMac until the four base bolts are back in place. One of them is used to squeeze the two halves of the heatpipe together, without which the heat won’t transfer away from the CPU and you computer will malfunction.
Mission accomplished.
Categories: Mac, mods, Technology Tags: , ,
  1. erik
    July 31, 2008 at 2:10 pm

    So, nanchatte, how about an update? Is all good and groovey with the iMac running 10.5 ? I have an iMac with 512 RMA and I’m considering upgrading the OS from 10.2.8 to Leopard, like on my mini ? Love to hear if your labours were worthwhile.


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