Ok so i bought 4gb RAM upgrade for my 20" iMac which currently has 1gb but when I installed the 2 sticks and started up my iMac all I got was a beeping sound. This freaked me out so I tried installing them again with the same results. Then I re-installed my original ram and everything started up fine. Can someone tell me what might be going on and what I can do about it??? Please help!!!!