Imac g5 first generation emc:2008 won't boot up

Use the Option key held down at startup again, to go to Startup Manager. Insert the original disc for Mac OS X 10.3 installation. It should appear in Startup Manager (you may need to click on the "refresh" icon). If it does, select it and proceed with the startup to boot from the optical drive. If you get to the Installer screen, at least you know your iMac is generally working.

From the Installer screen, go up to the Menu Bar and select the command to run Disk Utility In the sidebar, does the internal drive appear? If it does appear, does it have a volume (usually called Macintosh HD) indented under the drive?

If the drive does not appear in the sidebar, the hard drive may have failed, which would explain the "folder with the question mark coming up."

When you reset the SMU previously, make sure you used THIS procedure (and not the one for Intel iMacs)

http://support.apple.com/kb/HT1767

Try connecting the power cord directly to a wall outlet by itself (if you were using a "power strip") and initially leave all peripherals disconnected. Just connect the power cord.

Could this be because the harddrive is faulty?

Or maybe a faulty optical drive is interfering with the hard drive.

Has the PRAM battery ever been changed on this iMac?

If it's a first gen iMac G5, then it's the type that is fairly easy to open up and work on, internally. If that's your iMac type, you could try disconnecting the optical drive without removing or replacing it (in case some fault on the optical drive is causing this problem). Then, perhaps the hard drive will become accessible again. And you can also try it the other way, with the hard drive disconnected and the optical drive connected, to try a start up from your Mac OS X installation disc again (use the original one for this testing).

I would not buy a new optical drive, until you know with greater certainty that THAT is the actual problem. The problem could be on the motherboard somewhere, or the power supply...

Well, I was actually saying that you should not buy a new optical drive, because it could be something else, such as a problem with the motherboard or power supply (or some other component). I don't have "evidence" pointing to any particular cause, which is the problem here... and without knowing the cause of a problem, it's hard to fix the problem.

At this point, you may need to have a technician do a hands-on evaluation of your iMac. Or it could be time for a new(er) iMac.

One more thing you can try (as a long shot). Power off and take out your iMac's RAM module(s), visually inspect the connection area, and reseat them back in their slots. If that does not help, and you have two RAM modules, try starting up with just one module installed at at time, in alternating slots.

I'm trying to think of anything that might cause a problem during startup, that you have control over; the RAM thing is the only thing I can think of that you have not considered and tried.

I am experiencing the exact same issues with my imac g5 17 isight. Identical in all aspects. Did you ever find a resolution? Thanks