Computer won't go to "sleep"

[Schwann240]

I have a Power Mac G4 and just had to have the power mechanism replaced. Before this happened, I was keeping the computer on all the time (just putting the display to sleep), but now I noticed that now when it's on, it's much noisier than it had been before, so in System Preferences, I set the energy saver to have the computer go to sleep when inactive for an hour. But it is not working--the only way I can get the computer to go to "sleep" is by selecting "Sleep" from the menu under the apple icon at the top left of the display. I have tried it with several different settings, but it just won't go to sleep. (It has insomnia!) What can I do?

 

[simbalala]

Open up Activity Monitor, sort by CPU usage and check for some process which is keeping the machine busy. I have this issue with Safari when I leave a tab open to some websites, there’s a process keeping Safari busy at a low level.

You can then quit (or force quit) a process to see if it’s the cause. To test you may want to set the “go to sleep” time to a few minutes.

If nothing else works then you can try http://www.macupdate.com/info.php/id/27258/narcolepsy#descContainer_link">Narcolepsy 1.0

If I remember correctly this was available for 10.4 but the current version says 10.5

 

[macworks]

You might also need to reset the system management unit (SMU). It's also involved in controlling sleep. Here's Apple's article about how to do that: http://docs.info.apple.com/article.html?artnum=300341

Your computer might also be noisier if it's getting clogged up with dust. When it's full of dust, the fans have to work faster to move the same amount of air through. While a can of compressed air can take care of the bulk of the dust you would probably need two or three to get the job done well. I find that using an actual air compressor is the best option -- WARNING: Do not use an old air compressor or one that blows out condensation (water). ALWAYS spray some air out of the compressor first before spraying into the computer to ensure that any condensation has been cleared from the lines (I usually like the spray the air through my fingers so I can easily tell if water is present).