iMac Early 2009 restarting after RAM upgrade My iMac is from early 2009 and currently is running Mavericks OS X and has 2 GB of RAM installed. I then purchased 2 x 4 GB strips of RAM that were manufactured by PNY. Specifically, DDR3 RAM which is compatible with 1333 MHz and 1066 MHz.

Once I inserted the RAM into my system after removing the previous RAM, it failed after working for only 5 minutes. However, shortly after, the system rebooted and continued to do this until I shut down the computer on the 4th boot. I then reseated the RAM and ran the system again only to receive the same results. Now that I have replaced the old RAM, the system is working fine.

Does anyone know why this might be happening? Note: this RAM is brand new.
Remove one of the 4 GB strips of RAM so that you are only using half of the total 8 GB that you say you purchased. Does the system run stable? If not, replace that strip of RAM with the one you removed. If the system is still not stable, remove that strip from the slot and insert it into the other slot. If this still does not solve the problem, you may want to try a different brand of RAM.