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SSD upgrade on 2009 iMac 21.5" - success story


Standard Member
A few people have asked me to share the steps I took to upgrade my 500GB HDD to a 256 SSD in a 2009 iMAC.
There are plenty of horror stories about incompatible SSDs and whirring fans. I had no issues and this is what I did. It is well worth the effort. The iMac runs very fast again.

Upgrading my HDD drive to a SSD drive

Original Equipment.

Imac late 2009 21.5 inch
500GB Hitachi Hard Disk Drive
Memory 8GB (upgraded 2 years ago from 4 GB from Mr Memory)

Software downloaded prior to start

Ssdfanctrl Fan control (from exirion.net, google it)
Super Duper
Blackmagic Speed check from App store.
Hardware Purchased prior to start

Samsung EVO 850 250GB SSD. (PC World £89)
Sata to USB Lead (Ebay £2.99)

Over the course of the last month or so, I have:-
  1. moved my photos into Apple Cloud, and
  2. moved my itunes music and video library to an external hard drive,
I deleted the old files from the HDD. This took my storage usage from 450Gb down to about 100GB on the internal HDD.

You wouldnt need to do this if the amount of GB used on your HDD is less than the capacity of your new SSD.

On the day

Ran speed check using blackmagic to record speeds.
Shut and restarted computer to time how long it took to start up.
Attached SSD to imac using the cable bought off ebay.
Using Disk Utility, formatted SSD as “Mac OS Extended (Journaled)” and named new Partition as “Samsung SSD”.
Opened Super Duper and copied “Apple HD 500GB” to “Samsung SSD 250GB”. (This took about 4 hours to run.)
Using “Startup Disk” in System Preferences, set Samsung SSD as the start-up disk.
Closed and restarted PC from new SSD. This worked first time and I wasn’t bothered how long it took, although wasn’t long.
Closed down the imac and unplugged Samsung SSD from USB cable.

Fitting the SSD

Unplugged the imac from mains!!
Took glass panel off the front of the imac using a washing-up brush that happened to have a plunger on the end.
Removed the screen by unscrewing 8 x T10 torx screws, tilting forwards and unplugging 4 different connectors behind. (There are plenty of videos on youtube detailing how to do this.)
Put the screen carefully to one side.
Gently vacuumed the inside with a dyson v6 with brush attachment (optional!)
Unplugged the existing hard drive from Sata leads and temperature sensor using a small flat bladed screw driver.
Removed the two T10 Torx screws securing the hard drive bracket to the outer case.
Lifted out the old drive including the upper bracket.
Removed upper bracket from old HDD.
Removed rubber grommet from left hand hole. Drilled new hole, with 6mm drill, 76.5mm to left of right hand hole to align with mounting holes on SSD.
Refitted rubber grommet.
Realised old HDD used M4 mounting screws and the Samsung SSD uses M3, so can’t mount to bracket! No alternative screws included with SSD. :)
Attached new SSD to Sata leads in imac.
Held the new drive in place using a couple of cable ties. I was going to use double side tape, but that would force the SSD too far back in the computer and stress the sata cable. (I may go back and attach with M3 screws if I can find any (i think I need 10mm M3 wich I saw in B&Q))
Left the temperature sensor lead loose in case.
Put iMac back together.
Turned on IMAC to test it restarted.
Set the fan speed (Ssdfanctrl Fan control) to manual and set speed as 1500 (not sure if I needed to do this).
Shut and restarted computer to time how long it took to start up.
Ran Blackmagic speed check to measure speeds.

Results Before After
Time to start up 2mins30secs 30 secs
Write Speed 72.3MB/s 217.1MB/s
Read Speed 64.5MB/s 268.9MB/s


Distinguished Member
Nice. I'm deliberating what to do with my Mac Mini, as I think that after nearly seven years the disk may be on the way out.


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