My wifes IMAC wont start. What to do?

My wifes IMAC won't start which is a big problem for me. I hate touching her computer.

The original OS was 10.6 Snow Leopard but the only OS install disks I have is tiger 10.4.

I have used these to boot the computer and from there tried to do a verify and repair of the HDD but that fails with errors.

Is there anything else I can try to do to repair the OS?

I think I will need to format the HDD and install a new OS.

Is that so? I just want to make sure I have done everything I can before that

As the 10.4 disks are not the same as the existing OS, this means that I cannot Archive the existing OS and install the new OS in its place but must do a format.

How good is the 10.4 OS compared with 10.6? Is it worthwhile tring to track down some 10.6 retail disks?

Thank you for any advice you can give me. John.

Is you HDD healthy? Could be worth getting another if getting old. If you are starting from a CD/DVD then this bypass MACOSX on the drive. Normally when the lower disk begins a message comes up saying cannot load earlier. Have you had kernel panics previous or signs of faulty load ups.

In NZ, you can buy 10.6 direct from apple - here.

However, if after getting it and the 10.6 disk is also unable to repair the drive - would suggest replacing the drive - or at minimum, make sure she keeps current backups from now on - I never trust drives once they get to that point.

Replacing the drive in an iMac is no easy task - but you can search iFixit.com for tutorials on how if you've a mind to try.

I agree with Tom -- sounds like the hard drive needs replacing, and you should get a copy of 10.6 on DVD from Apple while its still available. With any luck, the data on the old one is still recoverable, but you'd probably be wisest to let an Apple tech find out.

I would never advise wiping the hard drive except as a very last resort, after you've given up on any hope of recovering the data on it.

Also, as an FYI: if the iMac shipped with 10.6, or if the 10.4 disks you have shipped with some other Mac, they will not permit you to install OS X from them.

Thank you all. $25 is not too bad so new disks will be the way to go.

The computer has been glitching for a while. Often when we were watching videos, the screen would go black and we would have to power off using the button on the back of the screen. After that it would often not start up again. And then a few days later it would start up fine.

Could that be some other hardware problem? Do they have a problem with video cards overheating?

I really wanted to use the 10.4 install to make sure there were no other issues.

But it seems to have no problem booting off the install disk so I guess it is a HDD issue.

If the original system was Snow Leopard as you say no putting Tiger on it OS X.4. As a rule of thumb no going backwards with operating systems. No drivers.