Your profile was created when you were using 10.5.8, I hope that since then you have upgraded to 10.6.8 or above.
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Troubleshooting: My computer won't turn on
https://support.apple.com/kb/TS1367
Symptoms
If your Macintosh computer won't turn on, here's how to troubleshoot it. Please keep in mind that although your computer may display similar symptoms that prevent it from showing video, this article discusses what to do if the computer won't turn on, meaning that when you press the power button:
- You don't hear a startup chime.
- You don't hear any fan or drive noise.
- The power button or power indicator doesn't light up at all.
If your computer doesn't display any video, it may display one or more of these similar symptoms when you press the power button:
- You may hear a startup chime.
- You may hear fan or drive noise.
- You may see the power button or power indicator light up.
If any of these conditions occurs, see
Troubleshooting: My computer has no video instead.
Resolution
If your computer won't turn on, try each of these steps:
- Make sure that the power cord is plugged into a working wall outlet, and that it's properly connected to the power adapter. (To check if the wall socket is working, plug in a lamp or other electrical device.)
- Make sure that the power adapter is properly connected to the power port on the side or back of the computer.
- Disconnect all accessories that are plugged into the computer, such as a printer, hub, or other mobile device.
- Reset the computer's PMU, SMC, or PRAM. Refer to the instructions for your model:
reset SMC For "Mac wont' turn on or boot" and related
Note: It is possible that the SMC could encounter an issue that may cause unusual system behavior typically related to the symptoms described below. In some cases, resetting the SMC may be the only correct method to resolve the issue,
https://support.apple.com/kb/TS1367
General purpose Mac troubleshooting guide:
Isolating issues in Mac OS X
Creating a temporary user to isolate user-specific problems:
Isolating an issue by using another user account
Identifying resource hogs and other tips:
Using Activity Monitor to read System Memory and determine how much RAM is being used
Starting the computer in "safe mode":
Mac OS X: What is Safe Boot, Safe Mode?
To identify potential hardware problems:
Apple Hardware Test
General Mac maintenance:
Reset SMC
http://support.apple.com/kb/HT3964
Resetting NVRAM
http://support.apple.com/kb/HT1379
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Install or Reinstall Mavericks or Mountain Lion from Scratch
Be sure you backup your files to an external drive or second internal drive because
the following procedure will remove everything from the hard drive.
OS X Mavericks- Erase and reinstall OS X
OS X Mountain Lion- Erase and reinstall OS X
OS X Lion- Erase and reinstall Mac OS X
About TimeMachine backups and Recovery Mode
http://support.apple.com/kb/HT1427
http://www.apple.com/osx/recovery/
OS X Lion and later let you:
- Start from OS X Recovery using your Time Machine backup disk. With OS X v10.7.3 and later, Time Machine backs up the Recovery System on your Mac to your backup drive as well. This lets you use your Time Machine drive to start up your Mac if needed.
OS X Recovery:
http://support.apple.com/kb/ht4718
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Reset SMC
http://support.apple.com/kb/HT3964
Resetting NVRAM
Safe Mac Guide
http://www.reedcorner.net/mpg/
(MacPerformanceGuide is also an excellent web site for ideas on upgrades and optimizing for application type uses))
http://www.macperformanceguide.com
Mac OS X: Starting up in Safe Mode - http://docs.info.apple.com/article.html?artnum=107393
What is Safe Boot, Safe Mode? (Mac OS X) - http://support.apple.com/kb/HT1564
Isolating issues in Mac OS X
Creating a temporary user to isolate user-specific problems:
Isolating an issue by using another user account
Identifying resource hogs and other tips:
Using Activity Monitor to read System Memory and determine how much RAM is being used
Starting the computer in "safe mode":
Mac OS X: What is Safe Boot, Safe Mode?
To identify potential hardware problems:
Apple Hardware Test
General Mac maintenance:
Tips to keep your Mac in top form
How to install OS X on a new or faulty HD without Internet recovery
Corrupt and new disks might not have a working Recovery partition, but there are still ways to access one and reinstall OS X, if needed.
Leaves out features and support for what to do when you have a good TimeMachine backup that you can boot from, though I would also prefer and side with "prevention worth a pound of cure" and why I preach having a clone of your system from when it was working order. Note: if you have a functional TimeMachine backup and running Lion or later, you should be able to boot from there.
http://reviews.cnet.com/8301-13727_7-57594422-263/how-to-install-os-x-on-a-new-o r-faulty-hd-without-internet-recovery/
https://discussions.apple.com/docs/DOC-3353
It's designed for those who already have a good familiarity with how Mac's work, is almost all Apple support documented.
If it's too much for you, there are local PC/Mac software repair and data recovery services, for hardware repairs you should take it to a Apple Authorized Repair. Please read the disclaimers at the bottom.
This User Tip is designed for Mac's that are capable of running OS X Snow Leopard (10.6) to any Mac running OS X Lion (10.7) or Mountain Lion. (10.8)
The Steps appear to work also in OS X Mavericks (10.9) at this time.