imac g5 produces humming sound after running for a while

I am facing some problem with my imac g5 computer. When I start the computer then it starts normally without any problem, but after running it for a while it produces "humming" sound. The sound does not stop once it is started. To bring the system back to the normal I have to restart the computer. Is there any way to solve this problem? The sound is irritating me a lot, so I need to solve this problem as early as I can. Do help me out. Any help related with this problem will be appreciated. Thanks.

After going through your problem I think the problem which you are facing either could be related with the hard disk for with the fan on your computer. So get your hard drive checked by the hardware engineer, if it is not your hard drive, then the problem is definitely from the fan. So try it out and see if it is able to solve your problem or not.

For solving this problem I will like to suggest you some fixes which you can try out on your machine. First you try to update the last version of Tiger from the internet. After doing that you might require to reset the PRAM and also make sure that the air vents are free of dust. Along with this you cam also try to reset the SMU on my machine. I think that after going through this two fixes you will be able to fix your problem.

I also have the same problem with my imac. In my case I get this noise when i watch streaming video on my computer. I have tried to reset the SMU, but it is not making any difference to my problem. I am facing this problem from the last 4 days and it is really disturbing me. Is there anyone who can help me with this issue? I will be eagerly waiting for your reply, so try to post it as early as you can. Do help.