I have an iMac G5, about 4.5-5 years old now. It frequently shuts off and often refuses to turn on. After completing a series of troubleshooting guides at the apple website, it appears I have a faulty logic board. According to the people at the Mac store, a replacement logic board should be $879.95 plus labor. I am assuming it is not worth it to replace the logic board (right?), but is there something else I could do to at least stave off the effects of the failing logic board? Or, is there some other alternative I have not yet discovered? Thanks.