Original post by: colleenthompson ,
The first thing I always do with a non-iSight iMac that is acting up is open it (there are three captive screws along the bottom) and inspect the capacitors. If any are leaking or swollen, that is almost positively the cause of the problem. You can get this repaired for around $250. There are shops that specialize in it. Much cheaper than replacing the logic board. If your caps are OK, then you can move on to other possibilities.