S.O.S.
Power supply was interrupted. Tried to turn on my mac. Just repeated the SOS code. Nothing comes up on the screen.
iMac, Mac OS X (10.4.1), Power supply interrupted
If by SOS sound you mean when you boot it just beeps at you, that would indicate a memory issue found during the power on self test. You can try reseating the memory, swapping memory cards, and substituting known working memory of the same type. If that doesn't work, and it's still beeping at you, take it in for service to an Apple store or Apple Authorized Service Provider. See this Apple note on how to remove/install memory: http://support.apple.com/kb/HT1423