IMac G5 froze and now it wont boot? Help!

Question

I have iMac G5, its 3 years old. I was playing a game and all of sudden it froze.
-First tried to resarted the computer, it wont boot up and there was no sound.
-Secondly, I manage to reboot, but it gave me the gray with Apple Logo and did not reach to the login screen.
-Thirdly, it booted up, though it was very sluggish and slow.
I manage to use Disk Utility, it seem to be fine. I shut down the computer it just froze.
I restarted the machine nothing, just a black screen. Only once I turn on with sound, still black screen and the FAN started to rev-up. I took out Ram from the machine and to see if I can restart it. I get power, No sound, and no gray screen. I have no clue what happen and how to fix it.
Any tips will be appreciated.
20 iMac G5 PPC 1.5GB Ram, OS 10.5.6
Thanks
Luis

Answer 1

Well, you could try booting from your install disc, and either running Apple Hardware Test, or using Disk Utility to try and repair the drive, but I still think it's the logic board:
1. Insert the Mac OS X Install disc that came with your computer, then restart the computer while holding the C key.
2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu. (In Mac OS X 10.4 or later, you must select your language first.)
Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.
3. Click the First Aid tab.
4. Click the disclosure triangle to the left of the hard drive icon to display the names of your hard disk volumes and partitions.
5. Select your Mac OS X volume.
6. Click Repair. Disk Utility checks and repairs the disk.
Then if possible, reboot and run Permissions Repair from your hard drive.
Let me know if you manage to revive it.