Ask Max: Apple RAM vs. Non-Apple RAM
It appears that some RAM has an Apple Logo, but others I've seen, are Hynix and Samsung, among others. Which brands do come installed in Macs.
Recently, a dear friend, who happens to be impulsive, decided he needed a MBP (sorry he went to Santa Monica, CA Apple store) so, then he shipped me his virtually new iMac Aluminum previous generation 2.0GHz, 20". I decided to put in another 1GB to make total of 2GB. I had this one, 1GB Samsung, from an identical iMac 2.0GHz, which does not have the Apple Logo, which my Apple refurbed, white iMac, 2.0GHz does have.
I installed this and it did not work!
Not all Apple-installed RAM has an Apple logo on it. In fact, most do not because Apple buys RAM from many different vendors and does not make any RAM on its own. The RAM you have should work, as long as it is still in good working order. If it was stored outside of an anti-static bag, the RAM could have been damaged. Also, you need to be certain that the RAM was fully seated in the slot. To test the RAM chip, a good idea is to remove the original chip and put this extra chip in its place. If the iMac boots up with your chip in it, then add the original chip back in the 2nd slot.