Does iMacG5 also have SMC like the Intel-based Macs?

My iMacG5 20" just 'died' on me yesterday. When I hit the power button it made the typical 'Apple' booting sound but then it turned silent and did not turn on. I turned the power off on my UPS then turned it on again and hit the iMacG5 power button after more than 5 seconds lapse. Then again and again to no avail. What could have just happened? Is it the end on my iMacG5?