Ram upgrade for iMac 21.5" mid-2010

[geraldm24]

Hi everyone,
I'm a regular visitor, but have never posted - I use this forum to find solutions for any problems I may encounter.
I'm now in search of a solution please... I was unable to find is upgrading ram on an iMac 21.5" mid-2010.


I bought a DDR3 4GB PC1333 CL9 ram modules.
The default size is 2x 2GB modules.

The iMac booted up, and the screen shows 12GB registered.
It then had a long BEEP (probably 2-3 seconds long, and repeating every 5 seconds, I guess).
When I removed the original 2x 2GB modules and inserted the 2 x 4GB modules, the screen showed the following:

Apple logo with the progress bar,
Blank screen with the cursor on the top left;
It then changed to the rotating colour ball.
Then a blank screen before the following message:
Your computer restarted because of a problem. Press a key or wait a few
seconds to continue starting up.

This whole process would repeat itself until I eventually switched off and reinstalled the original 2x 2GB modules.

What is wrong?
How do I know if the RAM is the correct spec (DDR3 PC1333, non-parity, unbuffered, non ECC, etc)?

 

[itareanlnotani]

Correct ram listed here - https://support.apple.com/en-gb/HT4255
Sounds like the ram isn't right. Return, and order more.

You need PC3-10600

You can't usually mix n match ram either, so buy all you need and sell the old ram.

Its about R1000 for 8G. eg http://www.takealot.com/crucial-8gb...0mhz-ddr3-unbuffered-non-ecc-mac/PLID30709643

 

[phiber]

If you're struggling to shop around, these guys are great. Type in your model number and they will ship you compatible RAM... I used them a few times, service is good as well. Called other Other world Computing, url below.

https://www.macsales.com/